Ah yes, for a start Tracker Control is even better than a Android firewall. If you don't have F-Droid, an alternative PlayStore installed yet, you can also get it here: https://play.google.com/store/apps/details?id=net.kollnig.missioncontrol.play

Exodus Privacy is a good starting point. They also have an app to check your installed apps with.
One possible next step could be to install an Android firewall like Netguard or Rethink DNS + Firewall to block unwanted connections. Both don't require root and are well documented.

The original overview dates back to 2023 but is updated, e.g. to mention EoL of DivestOS. Security updates are observed over a longer period of time. Its criticism is that though updates are provided monthly their release in comparision to the release of the patches is delayed by some days and sometimes incomplete. Can be compared here: https://source.android.com/docs/security/bulletin/asb-overviewand here: https://calyxos.org/news/The original overview in German can be found here: https://www.kuketz-blog.de/android-grapheneos-calyxos-und-co-unter-der-lupe-custom-roms-teil1/

I'd recommend iodéOS instead of /e/OS as the former is considered a bit more secure than the latter, see overview of Custom ROMs here (summarized from a well known German IT-Security Blog). You can also buy a FP5 with iodé preinstalled.

🤣

https://www.collaboraonline.com/collabora-office/
Works like a charme across major platforms and formats.

Last time I checked versions for Android and Linux were unpaid.

I have an Asus Eee PC from 2009 running Puppy Linux (as a secondary device).
As already pointed out you will need a leightweight distro and desktop environment.

https://distrochooser.de/(available in English) can help you find the right distro, it takes into account the age of your device, your Linux knowledge, use case and a lot more.

My data is my data. Period. Or at least it should be.
Abuse of position as dominant provider of search engine (incl. censorship) and mobile OS.
Labour Practice.
e.g. https://en.m.wikipedia.org/wiki/Criticism_of_Google

Similiar reasons apply to Amazon, Apple, Meta, Microsoft, PayPal, X and so on since well before Trump & Co.
e.g. https://en.m.wikipedia.org/wiki/Big_Tech

Appologies for my aggressive tone. I really hate these companies / their owners and what they are doing to our society, wellbeing, and humanness. It could have turned out so much different, if not for their greed and egoism!

My story is quite similiar, though I was working in theoretical ecology. Turned out that I could handle the computers we were working with and their linux distros better than anything else. I went on for another 2.5 years and then quit. I aquired he LPIC-1 and LPIC-2 certificates from the Linux Professional Institute, worked as a pure Linux sysadmin for half a year and am now working as a sysadmin for Windows in Linux in my 5.th year.
Where I live you need at least some kind of certificate (or some on the job experience) and the will and ability to learn. In my experience most companies that are working with Windows will be quite happy to hire someone who doesn't shy away from the terminal and/or cmd.