OpenWRT WIFI AP (and modem) for pfSense / Proxmox


I own a Proxmox homeserver now. I'm currently accessing the Internet through a Fritzbox 7590 DSL Router. I would like to hide my network beyond a pfSense firewall which runs on the Proxmox server.

So I would like to provide a WIFI AP for all the Wifi users in my flat. My requirements are:

-good performance, at least WIFI 5 or WIFI 6, if already available
-open source solution running on Open WRT
-must support mesh, at least one mesh device is required to expand the wifi to another floor

Are there any recommendations for a suitable hardware? Some WIFI router, or perhaps some raspberry pi with an optional USB Wifi card which supports mesh?

And can someone recommend a wired DSL modem online solution for the other side of the firewall, whithout router/wifi options, which I can plug on the other side of the firewall?

Many thanks in advance!