It will be greatly beneficial for my life and especially my privacy to self-host such software
You should go the Docker route. If you selfhost for yourself you can even use a Raspberry Pi or any common "mini computer" available. Just make sure to install a large enough SSD. 1 terabyte should be fine if you don't want to use OwnCloud or something like this.
The X1 Carbon Gen 6 is from 2018. If it was used since then it doesn't worth anything at all without battery replacement, maxed out RAM and a large SSD, even then, maybe 150 dollars max. If it is old stock it might still need a battery replacement and then I'd totally not pay more than 250 dollars.
Edit: I just checked PSREF: You're limited to either 8 or 16 gigabytes of soldered RAM. You cannot upgrade or change it.
The joke is the absurdity of a flat earth and making puns like "all around the globe" in that context and creating absurdist proof that the Earth is flat despite everyone knowing since kindergarten that it isn't.
I don't trust Mozilla one single bit with my data as long as they have an advertising network enabled by default and use pingback telemetry for ALL actions you do in the browser by default that can only be turned off by changing multiple "hidden" about:config settings.
I have to use Windows on my work computer and I am finding it hard to get FOSS applications on Windows that can do stuff like
The Gold standard in the screen recording world is OBS. It's not only available for Linux, but also for Windows and, well, is the gold standard. If you ask the question if OBS can do this-or-that regarding screen recording, the answer generally is yes (or "yes, via plugin"). Just use OBS on all platforms, it's clearly the most mature screen recording tool out there.
Something new to try/learn always motivates me.