Fans of any RPG system other than D&D and Pathfinder can have a tough time finding each other. Most often you have to convince your D&D/Pathfinder group to try something different. Maybe it works out, maybe it doesn’t.
However, I encourage all gamers of smaller games to play online, especially over Fantasy Grounds. Roll20 and Fantasy Grounds are excellent platforms for playing games with those already interested in the same game so you do not need to convince the group to play something they may be hesitant about. While Roll20 is good, Fantasy Grounds is my preferred platform. The fact that it has native Mongoose Traveller support only adds to my love of the platform.
If you are a fan of Mongoose Traveller but are not sure about playing it online, check out the Fantasy Grounds Academy. They have a video series about playing Mongoose Traveller 2e over Fantasy Grounds. Give it a watch and plan a campaign over this virtual tabletop platform.
If you already play your games over Fantasy Grounds, check out the JBE titles available there and download our Traveller, D&D 5e and 13th Age titles there, as well as battle maps and tokens ideal for ship battles in Traveller and Starfinder.