Really? My impression is that everyone is welcome. The only way I could imagine someone ending having a bad time there is to be hostile to other users.
Though you can subscribe to different communities and customize your experience, often what you can experience from specific community depends on which server it is located.
https://programming.dev/ and https://lemmy.dbzer0.com/ might be good for technology related communities.
As for fediverse a lot of depends on the server you chose, for example https://beehaw.org is much friendlier.