Venmo without transaction limits?

Check out Zelle, perhaps. Or just wire transfers I guess (see bill.com and others). PayPal for business is also alright.

Stay away from PayPal for anything involved in receiving money - they are notorious for freezing funds.

Businesses typically need a level of oversight, confirmation, traceability, and accounting integration that a service like Venmo doesn't provide. Even Zelle doesn't really provide this level of service yet.

Is there a reason standard ACH transfers via a normal business checking account aren't an option?

Monero Bytecoin (bad rap but stable) Aeon