I replaced the multifunction switch on my 2000 Blazer last year, the part was ~200 from the dealer and the steering wheel did not have to be removed.
However your turn signal switch is an older style similar to the one on my 1993 Caprice. Advance Auto lists the following switches to fit your truck.
The switches listed are less expensive ($40 to $70), but I’m pretty sure you have to remove the steering wheel to replace the switch though. If you can remove the steering column cover, try spraying the switch mechanism with WD-40 or electrical contact cleaner to clean the contacts first. A Chevrolet dealer should be able to look up the correct parts if you supply them the Vin number for your truck.
Good luck,
Ed B.