Good eye on that...a bubblenest wouldn't hold up well in a tank with a HOB unless the flow was baffled to the point that it's no longer doing the job.
I used to breed bettas and I would use golden pothos stems and hornwort in an otherwise bare 20gal that was half full. That's all till the fry were 3 weeks old, at which point i'd introduce a seasoned sponge filter. The trick is daily water changes rather than active filtration
Betta fry grow a lot slower without water changes...they produce a LOT of stunting hormones. I leave the tank at half volume till I put in the filter, then fill it all the way since the babies are usually hitting a growth spurt about then and need more stretching room.