I am successfully running Unifi (The TrueNAS one rather than the TrueCharts one) on my TrueNAS SCALE server without running MetalLB.
The Unifi web interface is available on the TrueNAS IP address, as are all the other ports that are needed.
The only difficulty I had was a result of my existing Unifi instance having died and I was therefore unable to export the site on there and reimport it on my SCALE box. (The old instance was on a Raspberry Pi and that instance died after Unifi created an upgrade which refused to load against the existing installed 32-bit version of Mongo and I couldn’t work out how to upgrade to a 64-bit version.)
I did have a backup of the Unifi config, that I could load, but without an export the new instance could not automatically adopt the devices and I had to SSH into each device and tell it the new IP address and port to dial home to.
But aside from that, I have no issues with Unifi under SCALE.
You will need to make your own decision whether to use the TrueNAS or TrueCharts version.
(I would be happy to share my Unifi app settings with you if that will help.)
I was stuck trying to expose the App with the freenas loadbalancer, but that wasn’t working. I’ll need to go through and utilize the truecharts app in places where I’ve already rolled FreeNAS apps
This may work but I also have external Unifi devices I manage. Going to each site physically or VPN for others would be more of a pain vs setting up MetalLB which took about all of 5 min following the guide. Currently looking to swap from FreeNAS apps to the TrueCharts Apps to support the network option needed for the config to work.