Do you know if it’ll affect my (personal) account? I run everything through a normal Gmail account and have forwarding for incoming email and an alias for outgoing stuff
It shouldn't affect you. DMARC policies apply to the authenticated domain, which is Gmail.
If you're using Gmail's “Send As” feature to use a different SMTP server for outgoing mail, then yes, you must have a proper DMARC TXT record configured on the domain you send from (even if it's just `v=DMARC1; p=none`).