No, you still need an external player. You can chose between VLC and Outplayer

It’s really easy to set up tho. You just open web,stremio,com and then add it to your homescreen. Then you just log in as usual and chose your external player in the settings. There is some kind of notification in the beginning which you can just click to never show again and ignore. That’s all

Stremio works over the web app. I use it, it works very nicely

You can sideload apps but it’s really annoying without having a developer account or without a bought udid (which is I think not really allowed). This would however allow you to have sideload more apps and you only have to refresh the certificates every year. You can still sideload with sideloadly or altstore but as I said, it’s really annoying because you need to refresh the certificates every few days and you can only have 3 apps sideloaded.

If public trackers offer you anything you want then not really. For me, I also sometimes use stremio and RD but most things aren’t available in my language. That’s why I now mainly use Usenet/private trackers and jellyfin

The only issue with stremio is that there isn’t enough non English language content available on public trackers

You definitely don’t live in Germany