No, Posthorn is outbound only. DMARC aggregate reports come back as inbound mail to whatever address you put in your rua tag and Posthorn has no inbox or IMAP to receive them.

Parsedmarc is still the right tool if you want to self host reporting, otherwise you should look into solving this with your provider. Explicitly trying to avoid dealing with all the operational costs of running a mail server, just trying to enable email capabilities in apps that need it so it's beyond the scope of what I built here.