Office Hours started running what are now called Hybrid meetings in 2019 when some of the participants were calling from Germany and China. It has gone rather well. Some participants join some weeks in person and other time from wherever they are
One factor is the chair being very careful to bring in the online participants. Polling them by name is a good approach and pointing out to them when someone in the room or on screen reacts or wants to comment. You have to be active in setting up a sequence of online and offline speakers. The killer is when it becomes a presentation. Try to never let anyone have the spotlight more than 20 min and then that is the extreme. 5-10 min at most is better and a fluid conversational exchange (1-2 min each) is ideal. These are all very event and group specific and will vary group to group and meeting to meeting.
Continuity between meetings is also important. Having a offline channels also helps; discussion/email groups, or place people can post follow-ups or introduce new topics to the group.
Lastly consider allowing others to lead; don’t keep the group leadership to a single person. Move the chair around and let others drive the conversation. Participation and ownership of the process and topics will keep people engaged regardless of the technology channels.