Linux

I recommend one of two Linux distributions, either Debian or Fedora. Both are well established, extensively documented and default to rather libre software friendly . Fedora does include non-free firmware on the install disc so it's a little easier to get going with on some hardware. Debian doesn't supply non-free firmwares on the default installer but you can download and alternate non-official ISO with the firmwares for WiFi, graphics and network cards that need them on it. Please note that not all WiFi or network cards need a non-free firmware so give the regular Debian installer a test first. In my personal life I try to use as little proprietary software, firmware and drivers as possible. I use both distributions on a daily basis and find both to be suitable for almost any task, although I have my preferences depending on what I'm doing. Debian is probably the most universal of the two and I run it on everything from single board computers, large multi node clusters, desktops and laptops. Although these days I've been preferring Fedora on my laptop machines for its more battery friendly out-of-the-box settings. I'm generally not a fan of derivative distros.

Obviously if you want to work in a big corporate environment check out RHEL or CentOS. Fedora is the basis of both of these distributions and tends to have far more up-to-date packages. I only use RHEL when it's specifically required for a project or a piece of software and prefer Debian for my own servers and infrastructure pieces.

I have a few old favorites I enjoy as well but aren't as beginner friendly nor as easy to manage in large production environments. Slackware is worth looking into for more advanced or more curious users. I ran it for years, even on servers. My time is rather limited these days and I don't have as much to devote to fiddling with things as I like so Slackware tends to live on one-off old test hardware. Alpine is another distribution I have been experimenting with lately too, but TBH I can't think of a reason to use it over a barebones Debian install.

Keyboards

Basically anything IBM buckling spring. Model F or Model M. If you don't fancy a vintage keyboard or want a more modern 104-key layout the Unicomp 2020 New Model M is my goto. These are not Model M "clones" as rumors claim. They are made in Lexington, KY with some of the equipment (the tooling has been updated for the 2020 M and Mini M) that the old Model Ms were by many of the same people. They are Model Ms.

If you need or want a TKL Unicomp also offers a Mini M now that is of the same quality as their full sized Model M. Both of these are available with Mac layouts too.

These do sound different than a vintage Model M but are still loud. The sound difference is mostly down to the changeover to vinyl backing material instead of the rubber used in IBM branded boards back then. Build quality punches above their weight, especially for what Unicomp is charging. They are still made of plastic but it's decent PBT so it's not such a big deal IMO.

Second place goes to the Alps based Apple Extended Keyboard I or II if you have to use a Mac for work or something. Alps switches are probably my second favorite but they are more problematic than buckling spring and Cherry. The AEK II used to be inexpensive and easy to find but not anymore. I've got a few other preferred Alps boards that I don't want to list and risk driving prices up on. I'd stay away from contemporary Alps clones like Matias as they have very high failure rates and key chatter problems. Original Alps aren't really that reliable either but they're much better than their modern counterparts. If you do get an older Alps board be prepared to replace or repair a switch or two here and there.

Mouse

I used to use whatever Logitech G518/G400 equivalent was floating around cheaply. They are wired, can switch DPI in hardware, are long lasting and comfortable for right handed users. For an ambidextrous mouse I like the very old school Micosoft Optical Mouse D66. No DPI switching on that model but they can still be found new old stock for under $10. Either is fine, I just like the feel of the Logitech for longer periods but I'm not left handed. I've used the D66 for years too.

Now I've become more fond of trackballs. Unfortunately they are less popular so options are more limited and the best stuff is probably only available used. The Microsoft Optical Trackball is the best and most easily found wired thumb ball these days. You will want to replace the likely worn out steel bearings with ceramic ones so factor that into your cost. It's not hard to do if you're comfortable with a screw driver and a small manual jewelers mini drill. Sadly all of your new options are battery powered wireless models. The Logitech M575 is a good value and uses a bog standard AA battery. The MX Ergo is not worth the price difference IMO mainly due to the non replaceable battery and the rubber coating. That coating feels nice but it'll turn to goo in a few years and get all sorts of dirt stuck to it in the mean time. I would only recommend it if you can find it refurbished or used at a significant discount, which is how I wound up with one.

Smartphones

If you don't have one don't get one. If you do have one get rid of it. In all seriousness I am the last person to ask you should ask. My only advice is that if you do have one of these infernal things don't let work/school use it for free. If your job requires some app or 2FA thing make a stand and get them to supply you a phone or an alternative means to work. There are many reasons to do this, not opening yourself up to liability and the company's prying eyes on your device is one but the more important reason IMO is to not normalize having a $500 spyware device on you at all times to participate in society. This puts undue costs on low income people and locks many people out.

Learn to live without it, remember how to be bored, don't scroll on it constantly, don't get too friendly with it and treat it as a hostile interference in your life because that is exactly what it is.