Does anyone actually sell a 'dumb' hard-wired Level 2 charger anymore, or is everything WiFi-connected now?

Grizzl-E Classic. No wifi, no app, set the amperage with a dial inside the unit when it's installed. It's been about as boring as you'd want a charger to be. ClipperCreek used to be the default answer to this question too, but they got bought by Enphase and I'm not sure what's still available under that name.

most of the smart ones work fine if you just never connect them to wifi. ours has never seen the network and charges every night

You're not alone in this. I spent a lot of years as a programmer, and "needs a cloud account to do its one job" is exactly the kind of design I'd go out of my way to avoid. Companies get acquired, servers get shut down, and suddenly an app update is standing between you and your car being charged in the morning. That said, a lot of the "smart" units are only smart if you let them be. Most will charge on plug-in out of the box with no account at all - the app is just there for scheduling and usage graphs, and the car can do the scheduling anyway. What you want to check before buying is whether the unit needs the app to *commission* it (set the max current for your breaker). Some do, and that's the part that would bother me. Also - and I say this to everybody - make sure you actually need L2 before you spend the money. My 14-50 install ended up at $3600 because of basement rewiring. Your mileage may vary, literally.