Canon has already returned to Chewbacca’s home planet in the Aftermath series, wherein Han helped Chewbacca to finally liberate Kashyyyk from Imperial control. The Wookiees are known warriors, and the Resistance needs all the help it can get right now. We already know that the Black Squadron was already out recruiting allies.
Perhaps Chewbacca brought a couple of companions to persuade the Wookiees to join the fight. (For the record – I don’t like the Chewie-Poe pairing. If Poe is with Chewie, and Rey isn’t present, that likely means Poe was piloting the Millennium Falcon, and that’s just wrong. The Falcon was Han’s, and should now belong to his surrogate daughter. Back off, Poe.)