Seems very niche -- you quickly leave the Zoom/Teams space and enter broadcast production.

Have a look at vmix [1]. That is broadcast production, and they offer a service called VMIX call [2].

There is a limit up to 8 callers in the Pro version.

[1] - https://www.vmix.com

[2] - https://www.youtube.com/watch?v=GMz6dZn7VOc