Fresh off the press is the Teams Developer Tool to create and share your very own backgrounds.
Take a look at the provided documentation, and have a go for yourself Teams together mode
For those organizations who want to control what their users are using as backgrounds and together mode scenes, this can be done by assigning individual meeting policies where the "Select video filters" is set to anything but "all filters".
The feature has just started rolling out, and it could be the end of July before the rollout is completed.