Your time, sold properly
Four emails to find an hour, one more to send an invoice, another to chase it. Or: a link that shows the hours you actually have and holds the slot once the card clears.
Bookings are included from Starter; Google Calendar sync needs a paid plan.

Google Calendar sync means nothing double-books.
Booking a slot generates the Google Meet invite for both sides.
Ask what you need on the form so you arrive already briefed.