zocster:
as much and as many your wallet allows, remember you can have unlimited aliases.
My single Google Workspace user account (mailbox) with 4 different aliases mismatching with 4 different domains. I don't use the primary account to communicate and that stays very private to me to use to log in. I set up the send-as for these aliases to send/reply emails from respective aliases.

And these are the domains set up to use Google Workspace.






