Putting random stuff into AP mode is sketchy, but usually works. Modern equipment in particular usually supports proper roaming, and clients are smart enough to change BSSID based on strength. Old and/or cheap equipment is less reliable because of poor or nonexistent roaming support.

If you want to do it the right way, get a couple real APs and pull Ethernet back to a switch. Ubiquiti is fine for prosumer, and you’re less likely to get “help my wifi stopped working and you need to come fix it” calls.

How many APs depends on house layout and what it’s built out of.