Absolutely, but you'll need to use the room code system.

The FitXR room code system for sending multiplayer invites is cross-platform, meaning Quest and Pico users can join the same multiplayer lobby. If you need help getting a multiplayer lobby started then you can read this guide.

The "Invite Friends" button that Quest users will see is a Meta exclusive feature, and so can't be used to invite Pico users into your lobby.

No problem at all, we've written a guide here that explains how to use your room code.