> Does anyone still use UEFI?

Yes. It's extremely common.

> If I start looking into the latest and greatest Qualcomm Nuvia ARM Windows laptops, does it use UEFI?

Yes, those use UEFI.

> Or regular BIOS?

Almost nothing widely produced today uses old "regular BIOS". Even those which seem to use "regular BIOS" are largely UEFI systems acting like a legacy BIOS. Even things like Apple MacBooks which don't use EFI use an Apple custom similar firmware concept far removed from legacy BIOS.