I was surprised to discover, long after quitting, that working full-time on your own ideas can come with it's own distraction: pressure to make money. Probably the biggest mistake I made from months 6 to 12 (startup idea #2) was being too concerned about structuring things in a way that would (hopefully) make it easier to charge money. I ended up spending a lot of time doing things that in hindsight weren't generating any value. It would've been much better to focus on doing meaningful things, whatever those may be.
I don't know the details of your situation, but that might be something to consider: if you can figure out a way to have a decent amount of time to work on whatever you want while still having an income from elsewhere, it might actually be easier to focus than if you were doing the idea full-time.
On the other hand, I am glad I quit myself. So maybe that advice is just BS.
For income: I might switch the "weeks/months" estimate to years ;). Running out of money hasn't been an issue (lots of savings from my job, my wife worked until recently, then we moved back in with my parents until the pandemic winds down). Opportunity cost of course is large, but that's fairly easy to ignore. I've learned an incredible amount during the past 18 months, so even if I can't get my startup to work, it'll have been a worthwhile investment.
I don't know if any of that is helpful. I'd be happy to chat if you like, my email's in my profile.