Netgate is providing a pfsense patch that disables ETM MACs but leaves chacha20 enabled. The vuln announcement is arguably vague because of the way is uses "and" and "or" but from the vuln scanner source chacha20 is clearly not okay even without ETM.

    https://forum.netgate.com/topic/184941/terrapin-ssh-attack

Shame they won't let me post a reply to let them know.