I like seeing the posts of people finding comfort with their new linux installs even tho they might appear a couple of times.
Linux is still considered a niche so the most likelihood of the newer folk appearing is higher then the more experienced ones. Also I wasn't always experienced and if it wasn't for newbie friendly content I wouldn't be here helping other people as well.
After all, information doesn't spawn out of thin air, it requires someone to carry and distribute it so that other people become also educated in those ways.
Which is way I find weird finding some people say "people are dumb they should do x, y or z cause its better" but then they don't provide any information and expect others to also know what they already know/have learned recently.
In conclusion, sharing is caring and I don't mind people sharing their experiences which also helps others on the same situation.
Still the exploit is easier to avoid compared to windows viruses and stuff. Even with the linux popularity increasing there is already out there good solutions to prevent this kinda stuff like have SELinux installed, use firejail to run suspicious files, use proxies to visit weird sites (you can use proxychains + tor, a bit overkill but works if you don't have a local proxy), etc.
Not to mention that one of the attack vectors of this exploit requires using a systemd feature which is the sysnetd which isnt going to work on other init systems. Reason why a lot of times minimalism can be superior to just having all the features + unnecessary ones out of the box.
Also found a relevant thread in LineageOS subreddit which claims that all of the apps are open source belonging to the AOSP or Android Open Source Project, and based on the contacts app it seems to be under the apache license (so it is Foss)
I not sure this is going to help but I use essentially all the default apps of lineageOS when it comes down to file manager, recorder and gallery.
But I do know that fossify has currently file manager and gallery apps which are very good, the recorder I don't really know a alternative.
Since I don't edit videos on the phone I can't really recommend an app but I am sure there is something in the fdroid repos or even on the github to install via obtainium.
If you are an advanced linux user then I would suggest giving a try to the following distros: arch, void, gentoo and (like you said in the post) nixOS.
The reason behind is that this distros are focused on the tinkering aspect of linux, the experience of setting up everything the way you want.
If you want to give a shot to WMs I would suggest i3, sway, dwm, dwl, river, bspwm, Qtile and hyperland (maybe focus more on the Wayland ones if you want to try the latest software).
Let's gooooo 🔥