I'm a Mikrotik user, not a Ubiquiti user, but looks like the closest match would be Mikrotik's CRS (Cloud Router Switch) line. My home network is a CRS317-1G-16S+RM at the core and three CRS305-1G-4S+IN (one in each room), all running SwitchOS/SwOS instead of the stock RouterOS (they dual-boot, your choice), and I am very happy with them.
If you can run RouterOS (you can) you can do all that stuff - switchOS is much more like a bare-bones packet switcher; RouterOS is a full-fledged network OS.
Yep, that’s how they come by default, booting into RouterOS. I prefer my switches to just be switches, though, so I run SwOS and do all that service stuff jailed on a FreeBSD router PC.
I like Aruba Instant APs, the kind that don't require cloud management or a separate controller, though it seems they've folded the IAP line into the regular AP line or something with their new Wi-Fi 6 gear.
I'm still using Wi-Fi 5 because it's fast enough and cheaper. My central AP is a IAP-315, an IAP-305 in the garage, and another IAP-305 at the wall by the back yard. They're all PoE and linked with wired backbone to form a single big coverage area using a single elected IAP leader as controller for the rest.
You shouldn't have trouble buying grey-market ones as long as you are careful to stick to the same regulatory domain for all of them. Aruba gear is available as USA/FCC, Japan, Israel, and RW (Rest of World) versions. I have operated RW units in FCC territory (proooobably legally but probably not worth the risk) by setting them to "US Virgin Islands" so they match FCC-allowed frequencies and power limits, but linking more than one AP still requires the hardware to be same regulatory domain.
