Can I use green wire in a residential wall box?

This is a 1985 home wired with typical NM-B wire and plastic wall boxes.

I have a few light switches around the house that have no ground connection. There are ground wires in the box, but the switches themselves don’t have a ground screw. I guess this was a valid thing to do at the time, but these switches need updating.

To ground the new switches, often times I need to run a ground pigtail from an existing wire nut to the replacement switch. And I’m running out of 14-gauge copper wire scraps to do that with. I’ve searched all the local big-box stores looking for 14 (or even 12!) gauge bare copper rolls, and I can’t find any. I can get insulated THHN or NM-B with no problem, but stripping eight inches of insulation off of that seems like a real chore unless I’m missing a trick.

One thing I did see — they sell rolls of green-insulated THHN in appropriate gauges and lengths. Since green universally means ground, can I use that for my application?

Separately from the question of whether it’s code-compliant to do, if a seasoned pro came by later and saw something like that in the box, would they think the previous work was done by a knucklehead? I ask because I’ve never seen green wire used in residential wiring, either in this house or anywhere else I’ve ever lived.