Hello and welcome. Shotgun and hammer are tanking weapons but certainly can be used for damage too, although consider the smaller attack range.
Shotguns are popularly used for their buffs and can be useful for healers/buffers too.
There’s no reason not to start out as dps and move towards tanking, but here are some of those guides to help.
The Ultimate Beginner Guide
Shotgun (dps) Shortguide
[Guide] Sustain-tanking for anyone