Apple TV 4K - 4 HomePod Minis - Xbox Series X

Hi. I have been scouring the internet looking for a method or explanation as to why this doesn't work. First I'll start with my equipment.

55" LG C4 OLED (OLED55C4PUA)

Apple TV 4K (3rd generation) Wi-Fi + Ethernet (A2843)

4 x HomePod Mini's (All purchased this year) (1st stereo pair named: HomePod - Front. 2nd stereo pair named: HomePod - Rear)

Xbox Series X

Nintendo Switch 2

3 x HDMI 2.1 (Zeskit MAYA - ULTRA Certified Cable - 6' long)

The goal is to get all four HomePod minis to play while using the xbox or switch 2.

Setup:

Apple TV is connected to eARC output on the LG C4 (HDMI 2). Xbox is connected via HDMI 1 and Switch 2 is connected via HDMI 3.

Apple TV Settings:

Apple TV and HomePod-Front are set as default for the room. HomePod-Rear is included in the room.

Video Audio > Default Audio Output is set to AirPlay with speakers selected Living Room (which is the Apple TV and HomePod-Front) and then HomePod-Rear is also checked. That currently provides two stereo sets to play together when watching regular Apple TV movies. I understand I'm not getting true front and rear output but it still sounds good.

What I'm not getting is audio from the HomePod - Rear speakers when playing the Xbox or Switch. As I'm typing this Im wondering if it's because by default the Apple TV and 'HomePod-Front speakers are linked together as a set and the rears are more or less a stand alone pair that's connected via AirPlay.

Is it possible to have 2 sets of stereo pair HomePod mini's connected together with the Apple TV? Or is it only one set? See image, you can see the Apple TV icon and HomePod-Front living room in one selectable spot. Whereas the HomePod - Rear is alone. Any help would be appreciated. I really hope Apple adopts the ability to setup front and rear speakers with Apple TV that would be wonderful!