Hicaithart, I don't know if y'all are still actively monitoring this, but a moderator in the Answers section of Microsoft Community suggested I post here.
New Outlook seems to be missing https://support.microsoft.com/en-us/office/keyboard-shortcuts-to-add-language-accent-marks-in-word-and-outlook-3801b103-6a8d-42a5-b8ba-fdc3774cfc76, that was available in earlier versions since I can remember. This is definitely a missed opportunity, as it is extremely helpful for multilingual users in corporate environments where multiple languages are spoken (extremely common in many parts of the world), since you don't have to switch keyboard layouts each time you need a specific accent/diacritic/special language-specific character.
Superficially, it seems like it should be low hanging fruit since it's already existing functionality.
Would love to hear your thoughts on bringing this back!
Milo.