[Klaus]

I'm still not sure whether this can be a really sustainable investment (reads: I would really use it beyond the initial rush).

I'm also wondering whether I shall start with the basics or - because if this is going to be a thing - with something that provides a little more.

A basic thingy would be a "Star Adventurer Pro" 
https://www.youtube.com/watch?v=JIwuidp9rCs
or maybe this
https://www.skywatcherusa.com/products/eqm-35-mount

I still have the old EOS 5D II which I could convert to Astro - although I may do that later on really.

I suppose that the start would be about some ultra-wide landscape shots and 300mm-ish nebulas.

Now ... can somebody talk me out of this to order to keep my sanity or tell me that this is not a stupid idea? ;-)