That's the problem with decentralized stuff, we can't detect it by URL anymore. We'd either need a centralized url (like mas.to), that stores your preferred instance in the cookies, or a local component/app that sits in front of the default Android Handler, queries all URLs, reads a specific tag (eg. service=peertube) and then suggests all apps with that tag. But that would need a lot of implementing and engineering on all sides.
Or all client apps implement support for all instances URLs /s
Yes. But again, top security is not a priority for many.
Actual security would be using a full disk encrypted linux device and storing it in your asscrack every time you don't use it anyway.
Geht das auch mit AVB statt Hash?