Becoming employed by a car company that wants to improve the experience of their vehicle is a perfectly reasonable option though. Or writing software for someone else's car - there's more than enough gearheads who'd spend a ridiculous amount of money on custom code for their vehicle if only they were permitted to.
Develop domain knowledge of the motor car. Ever more outlandish scenarios to enable you to make money from software in an open source way.
Well I want to develop software for devices people already have, their PCs.
Nobody but some software developers and those who don't want to pay anything cares if the software is open source or not.
Proprietary software has worked well for business for decades. It's more likely to be maintained and extended because it's paid for.
In my market there's cut throat competition between various proprietary software companies. All have developed software to migrate each others' data.
Don't like software A then go with software B or C or D.