I’m actually evaluating unRAID and NextCloud for that right now, but that’s still a few hundred dollar investment to get someting like that going and it still doesn’t deal with firewall issues.
Mostly I’m looking into this because I’m a paranoid idiot who thinks everybody is out to get my data. Well, that and I’m cheap so would likely choose the crapiest provider out there who would then close up shop a week after I finished my first full backup. 