Microsoft Teams
Add the app in Teams after it is in the tenant app catalog. A Teams tab and the SharePoint page read the same lists. There is no second database to sync.
Email delivery
Settings offers three delivery choices. Microsoft Graph sends with Mail.Send and only when that choice is selected. The From name is the signed-in mailbox. The Chronodat mail API and a Power Automate webhook are the other two choices. The app does not read mail.
Messages the app can send include a submitted listing, an approved listing, an expired listing, a saved-search match, a price drop, and a new message.
Microsoft Graph
The package requests User.Read, User.Read.All, Presence.Read.All, and Mail.Send. User.Read is the signed-in person. User.Read.All is the colleague profile, manager, search, and photo. Presence.Read.All is presence. Mail.Send is used only for Graph email delivery.