My kids are both definitely later like 11 or 12. We did all the things, including seeing if it was constipation, various alarms, etc. the only thing that worked was this specific alarm/underwear:
https://bedwettingstore.com/products/rodger-wireless-bedwetting-alarm-system?_pos=6&_sid=4fef05a04&_ss=r
They have kids and adult sizes.
It took a while and wasn’t perfect, but it taught them to notice the signals. It’s really hard hang in there OP!
We also got desopressin (sp?) from our doctor for the occasional sleepover, summer camp etc. It should not be used frequently, but it is OK once in a while.