Another alternative with calendar availability and scheduling is CalendarHero but it is $9 per user...
Nylas seems to provide the functionality I need. While prices are not disclosed, I will take it as a coding/integration challenge and figure out economics.
Spent 2-3 days hitting a wall on dynamic filtering of content (it's not supported by Webflow). Settled on using JetBoost, a 3rd party plug-in. It has also real-time search - neat!