Not sure of the best practices way, but resolved by:
1. opening Git Bash
2. cd'ing to the root directory.
3. Set up globals and origin (using set-url as it already existed. Globals
were probably already present, but when attempting step 4 prior to this
step, I was greeted with a username/password prompt).
* Originally wasn't aware that the user/pass was for http auth (which Visual
Studio must use). Probably an unneccessary step.
4. git push origin master -> entered passphrase
5. checked on Gitlab: the two commits had been pushed out.
was really hoping to see the 413 error message again but this time with hopefully more information, but there were no error messages encountered.
Going to mark as answer, but if someone knows of a more "built in" manner of handling this, I'd be more than happy to switch to that.