Sailfish as Linux Server?

It being a real Linux distro makes many things quite possible - though being a nonstandard distro, it may take some leg work on your end.

That’s some random mainstream app that does not sound like it would do any good running in the Android container. No real Linux version from what i can tell.

If you need a mobile router for something advanced and/or permanent; just get a purpose-built one and be done with it.

Both.