Yes, iD Mobile is a 5G network as of right now. However, it is introducing it gradually, initially presenting it on selected handsets and SIM-only offers before expanding to all.
iD Mobile was once one of the latecomers to launch 5G, with the four major networks, Three, EE, O2, and Vodafone, and a slew of different MVNOs beating it to the punch. iD has a 5G insurance checker as well as a list of useful gadgets.