Any recommendation on hardware piholes? I have a UDM Pro but honestly i don't know how much i trust modifying it at all - i've found Ubiquiti software to be iffy... so i'm a bit hesitant to modify anything.

I run two Pi4s with the filesystem on a usb drive, which is probably a bit overkill but I keep some monitoring on them too. In Unifi Routing, give the piholes a fixed ip and swap your dhcp server to have manual DNS entries - you might need to do this in the classic settings view.

I run mine on a good old fashion rpi for years with a 100% uptime.

I run 2 raspberry pi zeros connected (and powered) to my router as usb network devices both running pihole. I've been running this for years and have had zero issues.

You can run Pihole on any crappy raspberry pi you have around.

I ran mine on a Raspi Model B. You know, the one with the RCA plug and SD card slots. From 2012. At some point the SD was so messed up I couldn't ssh into it any more, but it still worked.

Now Pihole is running on my Thinkcenter minipc as a Socker image along with a good dozen others. I don't have to worry about SD corruption or sudden shutdowns any more.

there will be issues if you play halo. it depends on some telemetry stuff in windows that is typically blocked by this sort of thing.

I've been running a pi-hole for years and played Halo on Windows 10 and had no problems.

If you add a bunch of extra-aggressive blocklists maybe you'll have issues but if you stick with the recommended OOTB lists, you'll be fine.

Played 1 and 2 of the remastered edition, no issues here.