Unfortunately there's a lot of code out there that assumes commit hashes are case-insensitive and hexadecimal... I've written some myself. It'd be a hugely painful change.

Then you have stuff like 1, I and l, which are difficult to distinguish. Which was why base58 was invented (basically the range you suggested, without visually similar characters).

And zbase32 (https://philzimmermann.com/docs/human-oriented-base-32-encod...), which is my own preference for still being case-insensitive and thereby able to be used in subdomain names or email addresses.

This really should not be a problem since that's task #1 that a programmer's good font needs to solve.

I often run into git hashes places where a programming font wouldn't apply, like URLs and web pages.

>where a programming font wouldn't apply, like URLs

Any phisher's wet dream is a URL displayed in a font where l and I look the same. For anything that routinely displays URLs, font matters a lot. And any website displaying git hashes is likely to be programming related and have some code-font (good monospace or similar) in it's repertoir.