What OS version are you running?Do you have a sim card from another network you could try in the phone to see if its phone or sim related.What happens if you enable WiFi Tethering?
I have the same issue on a Pixel 7A. No 5G at all. (Have 5G on a Galaxy S24)Three had the same issue a few years back when they launched 5G, Pixels would not pick up 5G and Three had to work with Google apparently to enable support. I guess the same ...