Recovering from UDMPro Mistake

Yeah, I drank the Kool-Aid on UDMPro as a firewall… SMH
What makes it worse is I convinced a NPO, I volunteer at, to spend their limited $$$ on this thing. Love the AP’s and the UNIFI Switches seem to be doing fine and the management is great. But it ends there.

Can I keep the UDMPro and just manage the equipment and firewall (+ all other services) with pfSense?
Just pitch the UDMPro (ebay) and use the Unifi software controller?
Can I still get gateway access through with just the software controller?

(Another Lawrence)

I would ditch the UDM and get either a Cloudkey, load up a controller, or use HostiFi. All can be connected to the UniFi dashboard.