Just your friendly, neighborhood, geek who loves to crochet.
I think (but I have not tested) that if you can use the DeDRM plugins to import your books into Calibre... You might be able to use Calibre's conversion function to make them all ePubs (which are Kobo friendly). I don't have a Kindle but I do use a Kobo and have had to run DeDRM and some conversions to make books compatible.
Good luck!
Jellyfin? Or SubSonic? I don't know if SubSonic is still around, but I've heard good things about Jellyfin.
Ya... I'm with you 100%. It really feels like commercial software is the "minimum viable product" rather than a complete and quality piece of software. I've opted for FOSS solutions wherever possible for me and it has worked out swimmingly. Only place I'm still struggling is my home PC. Making the jump to Linux and potentially risking game compatibility is still a bit of a hurdle for me, but once my Win10 license loses support, Linux will be a very strong contender for my main OS.
Android auto definitely doesn't work (I tried Calyx briefly earlier this year).
What also doesn't work without a lot of finicky tricks is Google Calendar. I myself haven't quite gotten rid of Gmail and my calendar in Gmail yet, and that was a big headache I was not willing to live without just yet.
Outside of those two things it served my needs but I did not try any of the Microsoft products so I can't speak to those.
I use bypass paywalls clean on Mull by activating the Secret menu and choosing to install add-on from file. Works great for me.
Secret menu is in the About Mull page (tap on the logo 5 times) then back out to the settings pane to see some additional settings items added like install add-on from file.
How extensive of editing are we talking? If you just need some of the more basic features, there is Paint.NET which is surprisingly useful for a lot more than you'd think. Definitely not as feature-rich as Photoshop though.
I've not used it personally (I use Plex), but I have heard great things about Jellyfin. Does it maybe have the feature you need?
Jellyfin.org
I dislike Apple due to their user-hostile business practices. They don't let you install alternate browsers or keyboards (TRULY alternate and not just re-skins of Safari and the iOS keyboard). They don't let you sideload (officially). They don't want you to interface with other phone manufacturers in an equitable way (see the whole blue bubble/green bubble drama). They don't want you to have the freedom to repair your own devices (see the whole right to repair movement).
And so on and so forth. They are nice products and do what they are supposed to with minimal friction. I just cannot support a company that is so blatantly user-hostile.
I wasn't aware that we all had to adhere to YOUR standards of which softwares are useful/needed.
Sometimes people just want something. Maybe it doesn't align with what you want, but that doesn't make it wrong.