Minecraft cross-play with the same Microsoft Account

I’ve been looking for a solution hog this but don’t seem to be able to find a specific answer to this question.

My son has Minecraft for his Nintendo Switch.

I have Minecraft for the Xbox Series S.

We want to play on the same map.

When I was asked to sign in to Microsoft on the Switch I used my usual Microsoft accounti ie the same one that signed in to the Xbox.

I set up a multiplayer game on the Switch, but could not see how to join on the Xbox.

If I search for friends on the Switch it shows me my Xbox friends. If I search my gamer tag on Xbox, it says I’m already playing.

In essence: is it possible to ‘play with myself’ cross-platform or do I need to jump through more hoops?

As a side not to this I’ve also tried playing split screen on the Switch by detaching the Joy-Cons and using one each but it only seems to let me connect both at once. Do I need a separate controller to make this work?

Thanks.

:)