I am not going to discuss here various online video software or apps etc as this is not my area and will go straight ahead to ideas for what you can do to connect with others when you are on them.
This may be one for small groups or maybe 2 couples due to set up. Why not cook the same dinner as each other and get dressed up. You could even sit at the table and position the device opposite you as if they were at the other end of the table.
A simple one. Grab a drink (or 2 or 3) and sit on the sofa while having a chat with your mates from their own homes. I have done this one a fair bit in the last few weeks.
Haven't managed to do this one yet, although as a boardgame lover I'm hoping to do so soon. If you have the same game as a friend, then maybe you could both set up the board in your own homes. There are also some games with online versions that can be shared with others.
There are pub quiz type sessions that you can join in online or you can do your own. I know people who take it in turns each week to host the quiz or you could all choose one round to host so that you can then participate in the rest of the rounds.
The same as a standard book club but through your magical portals. Dependent on the club and how much time you currently have to spare, maybe you could meet fortnightly.
These are just some initial suggestions to get the ball rolling, I am sure that you can probably think of loads more.