These seem like they would be perfectly fine. All of the specs that matter for legality purposes are identical.
Several years ago I purchased thumb screws from McMaster Carr to replace the joystick battery compartment screw. No more need to a screwdriver and the thickness of the head adds just a little bit of pressure to the VEXNet key, making sure it stays in tight. At the time someone else had asked about these and they were verified as legal, but good luck finding that info from 5-6 years ago on the forum.
I forget the thread count and size, but here is McMaster-Carr’s page of thumbscrews. I also bought them back then.
We love those knurled head flat thumb screws too but they can be expensive when kids lose them.
Given only one year left until V5 comes out, I would just use a motor screw to get by.