I wouldn't drill the lid for a thermowell and ball lock port. There are a combo action of items on Amazon you could get and utilize the bung hole that already exists.

Homebrew #7 Stopper Thermowell

Stainless Carbonation Cap Counter

Home Brew Ohio Solid Rubber

Drill a 1/4" hole in the undrilled stopper for the carb cap and you have a ball lock connector.

The bung with the thermowell works great on my anvil fermenters.

bought this: https://www.amazon.com/dp/B01K4GGYT0

fingers crossed