Possible to Send Email as verified email identity vs. from verified domain?

Hello,

I'd like to send outgoing emails via WorkMail's SMTP server with FROM:(email that I own on a domain that I don't control), for example
from my.username@gmail.com.

I've successfully setup sending (and receiving) emails from verified domains. Domain verification is done via the SES console > Identity Management > Domains. So I understand WorkMail as being a simplified abstraction of the underlying AWS SES service - as WorkMail itself sends the administrator to the SES console for adding verified domains.

My problem now is: I'd like to do the same for a single email identity on a domain I don't own.

SES offers such functionality via SES console > Identity Management > Email Addresses and I've already added the example my.username@gmail.com remote mailbox and confirmed the verification email, etc. SES console shows this email as verified. Still, when I send email via WorkMail SMTP I get bounces like:

Unfortunately, the system was unable to deliver your mail.
The error given was:
2021-10-10 13:44:27 : You are not allowed to send as user or group my.username@gmail.com
You may need to contact your e-mail administrator to solve this problem.

Is it possible to send outgoing email FROM an email address I verified in SES (or somewhere in WorkMail) via Workmail or is this not (yet) supported by WorkMail??