[XaYdEk]

You bring up a valid point.

The ecosystem is going to be huge, so focusing on larger companies, with classical appliance lines (fridge, toaster, TV), that open source their firmware makes sense.

Within a certain product line code gets reused often, so you could work with specific product lines.

Also it really depends on how far you want to go with this and what options the firmware gives you to work with.