Watch SE hamstrung in "family mode" - any help?

We bought a SE model watch for my tweener son for Christmas as his intro to personal e-gadgetry without the potential issues that come with a smart phone. This was after some limited research of reviews, Apple’s marketing and in no small part to @ismh 's endorsement on a not too distant podcast (#554 maybe?), so I’m back here with an inquiry for any others here who bought a watch that another family member uses independently, but is paired to your phone.

The initial pitch for using this watch specifically was to give some of the phone functions to a family member who can’t / shouldn’t / won’t / etc use a smartphone, and specifically for kids who can use a device for the - how else to say it - less problematic functions of a typical smartphone. In these cases, the wifi/cellular watch has its own number and can communicate text and voice independently, 2 ways. Siri (or the watch version thereof) inquiries, weather status, sports scores are other functions which perform as well, and that’s fine.

However, there appears to be no way to sync music or podcasts to the watch, nor can additional apps be loaded onto the watch either. This is independent of the “schooltime” which allows me to (kind of) restrict access to phone use during certain times. I have no option, as the parent and user of the connected phone, to allow these presumably basic functions.

My calls to Apple support have been of no help (I actually had one support person tell me that it was not possible to link a phone with one phone number to a watch with another number) but it appears that there are unnecessary and inexplicable restrictions on the family sharing concept. To any other MPU folks who got the watch for their kids, how are you using it? Stymied, like we are? Or is there a better way to parentally monitor while still allowing (relatively) full functionality? I may be missing something obvious, or not so obvious, about settings etc., but music for example isn’t even an option in the watch app settings on my phone. Music is not listed as unavailable on the Apple watch support page.

Does opening the Music app on the Apple Watch show/reveal anything? Similarly, what do Siri commands to play music do? I think you’ll need Apple Music for the account that’s on the watch and maybe to set it up on another device (Mac?) so some preferences and favourites are there.

Thanks for responding; setting up a watch for a family member without a phone is a bit different from pairing a watch to a phone for the same user. Set up an Apple Watch for a family member - Apple Support
The music app does open on the watch itself with an option to choose playlists for example, but no apparent method for syncing those playlists. An Apple support answer from the website advises to open “music” in the watch app settings on the paired phone, but as you can see below, that isn’t even an option. I have sent emails to support and feedback to no avail. We have shared music for all devices in our network too. Not sure how to “set it up on another device” either.

The person has to have an Apple ID though to have the watch. If you sign into that Apple ID on a Mac with Music, can you set up playlists which then sync to the watch?