The best example that comes to mind is Ardour, a FOSS digital audio workstation that charges for binaries. Their FAQ says

If you want the convenience of using our ready-to-run version and/or for support from Ardour developers and experienced users, we ask that you pay something for this.

If you don't want to pay for a ready-to-run version, then you'll need to get the source code and build it yourself. We do not provide assistance with this process and particularly on Windows and macOS this can be challenging and take a long time. Also, for Windows, there are no instructions.

It’s a bit mixed in with the “pay for support” model, since you’re basically on your own if you build it yourself. Which probably makes support a lot easier, since there are fewer supported configurations. This seems like a pretty workable model for something as complex as Ardour, but idk how well it would work for simpler projects.

think it also helps that Ardor is used directly by individual users, and its proprietary competitors are often quite expensive. If you’re making something that already has a lot of “free as in beer” competition, this may be harder to pull off.