Neither microkernels nor rust will help if you can't get everybody to agree on an ABI, which is the hard part in the first place. That said, if you're willing

Neither microkernels nor rust will help if you can't get everybody to agree on an ABI, which is the hard part in the first place. That said, if you're willing to deal with other people's APIs, NetBSD's rump kernels are good for providing reusable drivers, and some projects have even had luck pulling drivers out of Linux to reuse, though obviously that's a little bit touchier.