This is just my personal thoughts, don't claim that are universal correct:
At this point I see the use of Jetmouse software only to create codes for TMC receivers. For maps, I am using the unlocked maps with no problems.
I don't agree with your justification. Now you say that you want to provide proprietary/selfmade maps... OK. For all that I know, Garmin devices will continue to function with a deprecated map, it is left to the users the update choise. So, IMO, you want to criple the device on purpose and the potential client might not be aware that your product wil act different than a regular Garmin map.
PS: Maybe you can send some of that cash flow to jetmouse or tom1807 and you will get your personalized app.