If we wanted secure products, we wouldn't ban devices. We'd mandate they open their firmware to audits.
problem is: how do you prove the firmware in the flash chip matches source? And I do not mean me, with a disassembler and a pi pico to read out the flash chip. I mean the 70-yaer-old corner shop owner that buys this router to provide free WiFi for customers?
A trusted website that compiles it from source and a way for you to go to a webpage and flash from there automatically. The FPV community does that all the time with a set of websites for their ESC, flight controllers, radio, all open source. You can add signatures etc but just a trusted website goes a long way vs a random blob preinstalled