The new appointment scheduling is a great addition to the Proton Suite! However I agree with some other suggestions here that there are a few features lacking at the time of launch.

Here are a some things I find missing that would be great additions, that I haven't already found suggestions for:

• Larger selection of appointment duration (e.g 15 min, 20 min, 40 min, etc), or custom input

• More choices on "How far in advance can someone book?", or custom input

• Ability to customise the content of the confirmation email would be great

• Have the subject of the confirmation email be the name of the appointment they booked:
  Let's say my booking page is called "Consultation", the subject of the confirmation email should be "Invitation for Consultation starting on [date] at [time]" instead of "an event"

Here are the other suggestions I've found interesting that you might want to vote on (hope I'm allowed to link them like this) :

https://protonmail.uservoice.com/forums/284483-proton-mail-calendar/suggestions/51180499-calendar-booking-page-treat-all-day-appointments

https://protonmail.uservoice.com/forums/284483-proton-mail-calendar/suggestions/51182317--more-flexible-start-times-on-booking-pages

https://protonmail.uservoice.com/forums/284483-proton-mail-calendar/suggestions/51182617-hide-account-email-on-booking-page

https://protonmail.uservoice.com/forums/284483-proton-mail-calendar/suggestions/51170881-description-field-in-booking-page

https://protonmail.uservoice.com/forums/284483-proton-mail-calendar/suggestions/51177115-booking-calendar-free-time-before-and-after-a-b

https://protonmail.uservoice.com/forums/284483-proton-mail-calendar/suggestions/51185167-appointment-scheduling-feature-in-proton-calendar

https://protonmail.uservoice.com/forums/284483-proton-mail-calendar/suggestions/50550987-meaningful-subject-line-for-appointment-reminder-e