Auster

I wish Kbin allowed disabling picking the blurb's body of text X'D

Any with good hardware as long as you can switch to stable and community-made ROMs.

Can't disagree, UI still hurts the eyes, and I've been using it since 2021. "<.<
Still, so far, it appears legit through comments I saw from quite a few developers and users.

Bandcamp, Supraph Online, Ototoy, Uta 573, Steam and GOG's OSTs and Apple's iTunes store have been my to-go options. No DRM, no worries. Just avoid Apple's music subscription, as it is DRM'd.

By this logic, demos from GOG could be posted too, since both are appetizers for something else (in Prime's case, an appetizer for the paid service), and both can be claimed.

Prime is a paid subscription, so users would need to pay to be able to get the game.

If you like reading books, comics, etc, maybe Librera Reader?

Dunno how it is on Google Play, but it's available FOSS and DRM free outside of it:
https://f-droid.org/packages/com.foobnix.pro.pdf.reader/

Since 10 y.o. is old enough to be a cutoff for me, PS Vita, and because modding community never stopped. You can even play some Android and PC games through wrappers in it. *-*

Duolinguo feels more like a very annoying ad than a learning tool, often under-explaining what it tries to teach while heavily penalizing and shaming the user for getting things wrong.

What I would suggest, other than hiring an actual teacher, would be to immerse yourself in works from their language, such as music, comics, books, movies, and so on. Also, Spain's Real Academia Española has a dictionary+conjugator site that is VERY helpful, even for "dialects" such as the Latin America variations (link for the tool is dle.rae.es). Finding someone to try to talk to in Spanish may also help, although getting to know some of the grammar beforehand is advised.

Now, as for either free or FOSS programs specifically for learning the language, sadly, I'm not aware of any.

Opa

Olha, estou confortável com usar pelo navegador então nem fui atrás de aplicativos.
Mas ao que tudo indica, o Kbin permite gerar um feed RSS, então pelo menos publicações podem ser vistas em outros serviços.
E imagino que, tal como a concorrência, tenha um API público próprio, então talvez tenha aplicativo próprio também.

Linux systems are usually laid bare for people to tinker with, which for me is specially good if I see something I don't like, be it software, UI or UX.

Plus, most PC's I've seen from at least the past ~20 years can run Linux, so if I get my hands on a working PC, Linux becomes an easy choice.

Plus², Linux can be made very privacy friendly.