[tenebrisalietum]

No. This concrete example illustrates my intended meaning:

Asus has a couple of Wi-Fi access point/switch/router combos with their own Tomato derived firmware named AsusWRT. It's nice. Because it's GPL, the source is required to be available, and a project for a derivative firmware named Merlin exists. Merlin provides additional features. One can choose to flash this firmware if desired.

If these devices must only accept signed firmware then the above becomes practically impossible and you cannot control the software running on your own device.

[repelsteeltje]

Ah. So essentially, malicious compliance with the open source requirement, using DRM/tpm. Probably under the gise of SECURITAHH...

Yeah, I can see that. Might be remediated using legislation as well - mandate free access to third parties. The point being that (open) software development can continue maintenance beyond vendor support for the hardware.

But yeah, that would still need some story - and clever thoughts - about authenticity and trustworthiness of the firmware and how to technically enforce them.