How about we let them flash the ICs that they have first? Or allow them to change the maximum speed on the vehicle without having to go to the service center and paying 300 to 500$.
Why are we talking about low cost at home IC development for farmers while we don't let them do even that.
Forcing companies to open source their software is not possible, but making sure we can replace each component after warranty? There are strong right to repair movements, it's just matter of time.
But you still have to reverse engineer the IC before you can replace it - and once you have that it's still cheaper to have it manufactured in an existing Fab than to build your own.
Forcing companies to open source their software is certainly possible for some senses of the word "possible". You could go a long way in that direction just by changing the copyright law to not cover software, or to only cover software if the source code is deposited with the Library of Congress. Or you could change product liability law to declare products shipped without complete, compilable source code for their firmware to be "defective". Right now the political support for such changes isn't there, but that can change over time.
More likely we're going to go in the opposite direction, though.
Why are we talking about low cost at home IC development for farmers while we don't let them do even that.