I stumbled across one problem - the niche is so specific, that I'm not able to find other niche relevant websites.

I even tried to look at the most difficult keywords to rank for - top results, and they have also very few backlinks from actually relevant websites.

Do you think it's good idea to still pursue links, from a little bit less relevant websites? For purpose of an example, let's say that you have a blog about table billiard - is it a bad idea to reach out to sports websites for a guest post for example?

Or is it just me overthinking stuff?

I will appreciate any advice :)