Just to add to Bob's comment.. nothing wrong with using Airport routers if you already have them.
Since Apple ceased production >3 years ago don't buy second hand ones (or overpriced new) as they are not worth it. The exception is the Express for Airplay duties only.
Apple sells Mesh wifi from Linksys.. the Velop product line.. and previously sold a few others although it seems Velop only now in some stores as being compatible with Apple home kit
Just search for
linksys-velop-ax4200-wifi-6-mesh-system-3-pack in apple store
So this is only relevant to using or reusing Airport routers you have or obtain for pennies.
The limitations are clear and obvious but for most people of little consequence. i.e. WPA3 wifi security is only relevant to protecting your network from neighbours in wireless range. If you live in Apartment building then that can add up to lots of people and some you may not know or who change over rentals at frequent intervals. On the other hand for most people in free standing house in suburbs then you only have 3 or 4 houses in wireless range usually. Hopefully also people you know well and have some idea of their honesty quotient.
Security of the Airports from internet attack is still good assuming you use long complex passwords and good housekeeping on the network. Many of us still use Airport routers behind another brand main router for airplay or Time Machine backups which is not a problem. Using anything other than Time Machine is not recommended e.g. windows computers would need to run SMB1 which is deprecated on all OS now.