I wonder if you can just backfill "activity" by just setting the time on your commits:

Generate a list of all the files in the git repo.

Delete the .git dir

git init

Commit each file with a date in the past with some kind of bash one liner feeding each file into:

git add filename && git commit --date "X day ago" -m "wrote filename"

git remote add origin

git push -f -u origin main