I tried all kinds of things on unrooted phone. There was a time when it worked with a particular version of the Health app for a couple days. Then I was never able to get it to work again, virtual explosed, frida etc. None worked. I rooted my phone 2 weeks ago and I am currently on Havoc 3.8 and decided to try this again yesterday.
I installed edExposed (plus core), rebooted. I installed the apk from this thread and enabled it in Exposed. I had just cleared data and cache and uninstalled the Health app and reinstalled it after edExposed and the apk were in place. I am now able to go to devices/watch/help/watch faces/watch faces/three dots --> upload watch faces and upload a single watch face. Good enough for me, especially since it's working on the latest Health app from the store (US). I'm not changing it daily, so this is cool for me.
cheers