According to this [1] Alphabet had 100bn in cash on 2019 so it seems something possible.
Is it just a regulatory matter? Why would regulators care on who owns a bank?
[1] https://www.cnn.com/2019/02/04/investing/google-alphabet-cash-dividend/index.html
If I had to guess, probably the other way around. Banks have obscene amounts of regulations, audits, compliance that would seem archaic and insane to most tech companies. This is already baked into banks operating expenses and procedures. Tech companies would have to take on massive amounts of cost and this would affect their reported earnings. Then there is the aspect of operational speed, agility, speed of R&D. Banks move incredibly slow because of the compliance burdens, at least that was my experience.
what a bank does. which is lending out other people's money. most governments want to be quite sure who its lent out to.