I keep seeing this, but I've never signed into a single one of my banks, mortgage companies, stock brokers, or credit card companies on my phone. The phone might be used to get a code for 2FA via text, but that's the extent of it. Everything is done on my PC through a dedicated browser specifically for financial purposes. This applies to Chase, Fidelity, Schwab, Wells Fargo, Marcus, Morgan Stanley, Amex, and more. So theoretically there's no reason a Linux OS on a phone can't do any of these things without Google or Apple by simply masquerading as a PC.