The USG3P can do gigabit (I get very close to gigabit speeds in internet speed tests - ~950/950) but I can’t use IPS/IDS without severe performance penalties. It basically becomes a fancy router with little in the way of actual “security” besides its basic firewall functionality.
I am aware of the UDM Pro and USG Pro but those things are expensive 1U monsters. Maybe fine for SMB use but this is for home use and I’m very space constrained.
If Ubiquiti made a small footprint security gateway with some modern hardware (the USG3P is some 8 years old at this point!) I’d buy it in an instant.