Does Revyn write anything into Salesforce?

No. The Salesforce connector is read-only — contacts and opportunities in, nothing out.

Can I connect with an API key instead of OAuth?

Not for Salesforce. Each org's API host is only discovered during the OAuth token exchange, so a pasted key would have nowhere to point.

Contacts and Opportunities. Accounts are not read in this version.

Contacts and opportunities over the REST Query API, read-only.

ContactsBecome prospects a rep can prep for and practise against.
OpportunitiesStage, amount and close date, feeding the deal loop and outcome analytics.

Nothing. This connector reads Salesforce and writes nothing back to it.

Accounts are not synced. Company context comes from the contact and opportunity records instead.
Nothing is written back to Salesforce. If you need a call's analysis on the record, HubSpot and LeadSquared are the two connectors that do that today.

Does Revyn write anything into Salesforce?: No. The Salesforce connector is read-only — contacts and opportunities in, nothing out.
Can I connect with an API key instead of OAuth?: Not for Salesforce. Each org's API host is only discovered during the OAuth token exchange, so a pasted key would have nowhere to point.
Which Salesforce objects does Revyn read?: Contacts and Opportunities. Accounts are not read in this version.

Connect Salesforce in about a minute.

OAuth only, with the standard `api` scope. The per-org API host is learned during the token exchange, which is why there is no pasted-key path.