I've know some local orgs that could absolutely make use of a shared bank account for accepting and dispersing donations for mutual aid. The problem is these orgs are far too small to incorporate into a legal entity, have a stable mailing address, or even an official phone number. Only thing that's stable is an email address.
Most common solution I've seen is one person just has all the money. They setup a PayPal account and are responsible for receiving and dispersing all funds. This obviously isn't very secure. First there is the obvious risk of embezzlement. But assuming you've picked a trustworthy comrade, they're now more exposed and there's severe consequences if something happens to them. Like if this person is running a bail fund they might get hit with bs RICO charges and you lose all your donations.
I've tried to setup a PayPal using a google voice number but PayPal seems to recognize and block that. Crypto is supposed to address this issue but we still need dollars in and dollars out so that might be more complicated than worthwhile.
Any ideas or experience with this issue?
You might find a 501c3 that will have the ability to "sponsor" you, and have a babk account suffix dexicated to your micro-org. If you're a bail fund, though, that might be a liability, and attract the ire of the Once and Future President on that nonprofit.
My local DSA chapter is absolutely capable of doing this and there are groups that aren't a big risk. But most of these groups have strong anarchist tendencies and take their autonomy seriously for more than ideological reasons.