Good idea
Don't know if I ever seen a propane detector but I'll check various plug in detectors.
Just bought one. Gas was leaking in my office from a newly installed gas meter outside my window. The gas company replaced a fitting and the smell went away.
I don't trust big companies so I bought a gas detector. If I start getting alerts I will encourage them to move the meter to a safer location.
I bought a First Alert. It detects carbon monoxide, propane and natural gas. It got good reviews. It is a plug-in model. The reviews also said it eats batteries so we shall see.
By the way, you open the cover to acces the battery compartment with the tab on the bottom right. I accidentially tried to open it from the hinges on the top.