I agree with the two approaches. I have never worked with FAANG, but I have worked in adtech and I felt suffocated. Open source (or source available to keep big vultures away) can surely work as a sustainable business model, just that this takes longer to develop.

If I chose to not have lock-in in my products, to encourage people to self-host and own their platform/data, of course it will not allow me to scale to unicorn status. But that is not my target. I would rather see people use my product, pay a fee voluntarily, and not be locked-in.