While I agree with you in principle, in practice Google makes side loading so convoluted and scary that I think they do need / deserve some censure here. The fact you have to go deep into settings, toggle weird settings that tell you how dangerous it is to side load and then it toggles the setting back after you put it on without asking you - this is not all that different to Apple letting you use an alternative payment provider but putting so many warnings in place that no user would ever do it.

I want Google to make ability to side load an actively supported first class feature of the platform. There can be a warnings and additional security measures (scanning, permissions boxing etc if necessary) but nothing that in practice has the effect of preventing a commercial entity from shipping a functional app outside of their store.