Connecting Oticon hearing aids with a cellular Apple Watch series 8

I own a iPhone 13 Pro Max and recently purchased Apple Watch series 8 (cellular version)

I am also using Oticon more1 hearing aids and have the Oticon ON App on my iPhone and it also shows up on my Apple Watch and works well when the mobile is ON and close by.

Once I switch off the mobile and at the same time switch on my cellular on my watch, Oticon ON App disconnects along with my bluetooth hearing aids. I tried to ‘add a device’ but cannot find my hearing aids. I notice apple Airpods do show up. 

On my iPhone accessibility, there is an icon for adding and pairing hearing aids. This is what is missing in the Apple Watch.

Can anyone help and let me know the solution how I can use my cellular mode Apple Watch with my Oticon bluetooth hearing aids when my mobile is not close by?

C.D.