git cat-file commit HEAD
to see something like: tree <tree-hash>
parent <parent-hash>
author <author-name> <author-email> <timestamp>
committer <committer-name> <committer-email> <timestamp>
gpgsig -----BEGIN PGP SIGNATURE-----
<ascii-armored RFC9580 signature>
-----END PGP SIGNATURE-----
<commit message>
You can view an example of the structure of this ascii-armored signature here <https://cirw.in/gpg-decoder/#-----BEGIN%20PGP%20SIGNATURE---...>.