> "Alt Codes" which are the majority of (my) shortcuts? e.g. Alt + H - I - S for Insert Sheet

Alt + H opens whatever menu H stands for, then the subsequent letters hit the appropriate menu items. The menus and their hotkeys would have to match the Office counterparts as well, and that's unlikely in normal free software clones. Not sure if it'll be that case here.

edit: After looking at what this tool does, I actually would not be surprised if you could just rewrite all the menus and their hotkeys...

Yeah, I do/did doubt this would port over the Alt Codes, though as you say I'm not sure someone couldn't just long-hand re-write the Alt Codes in either a mod/add-on/config file for any given Office competitor suite.

After all, the majority of the "mappings" are arbitrary/obscure anyway as only one option can "match" the letter (e.g. F is for File, so ForMulas needs to use M. I and D are used for legacy Office Shortcut compatibility so iNsert and dAtA use N and A respectively).

In other words, looking for a logic to these codes even in Office is a hiding to nothing anyway and it's really just a case of building muscle memory (or coming up with a bizarro-logic that helps e.g. "A is for dAtA").

It would be incredible to just be able to install a "365 Mode" or config where the full re-map has been done. I'm semi surprised this hasn't already existed for a long time, even to the point of being shipped built-in.