Keycastr (Open-source, free)
Mouseposé (Annual subscription, additional mouse features, free trial available)
Keystroke Pro (Paid, no subscription, light/dark themes, focus on design, free trial available)
You can alternatively show the on-screen keyboard but this is extraneous for my use case.
Note: These apps are all listed in this question which ...
My solution is to work with my partner and show them the on screen keyboard viewer and talk / slow down when they are new. Also, empowering them to interrupt you, asking if you’re good to proceed and asking if they want to review any steps, they’ll let you know when they get the key shortcuts and then you can close the keyboard viewer.