Porkbun is owned by Top Level Design registry, so they've been around a fair while. From what I know, Top Level Design / PorkBun own the TLD's of .ink, .wiki, and .design, as such they are the registry for those TLD's.
Anyway, they are ICANN accredited.
The owner says
Our pricing model is really simple, we just put a $1 mark up on non-premium domains (after CC and ICANN fees).
They don't have enough TLD's that I use to move to them. Their pricing is great, though.
Considering Namecheap still resells through eNom, PorkBun probably won't run away anytime soon.