The issue I'm running into is I see pieces and references to electrum but I'm wondering if there are any beginning-of-file bits or common hex strings that I can search for which would show me the beginning of a wallet file.
I think it's a random string you can't just easily find them by searching it through hex strings there is an old discussion about this that you can find here "
Hex pattern for electrum wallet".
Check the post by HCP it should explain about the wallet file with different hex strings.
The easiest one that I can suggest is to use a search tool just like what I said before if you have already done that thing then possible that you named the wallet file with a different name. 20TB is such a huge drive the software that I mentioned above I tested it for big drives to find the right file you can try the
advanced search.