Fireplace turns on by what looks like a normal light switch. Sometimes takes 20 times to get it to catch. Had a tech out and he gave everything else a clean bill of health. Said the switch is bad. Not sending the "right" current to the unit that starts the fire. But he didn't have a light switch to replace.
My question is will "any" new switch work or do I need to take the old one with me to seek the replacement. Or are there differences in "normal" light switches?

The one I've seen used a standard single-pole "light switch". It either opens or closes a set of contacts for two wires. (It could also have a grounding wire that makes no difference.) Might be labeled 110v-15A.
If that's what it looks like, I'll bet that's what it is.

Replace it with a standard switch.

You could verify operation by bypassing the switch, to confirm its the problem.