Ordnance Survey maps on fenix 6 pro?

Hi

I've recently acquired a fenix 6 pro.  Very happy with it and finding my way around it.  The cherry on the top, however, would be the ability to view / use the Ordnance Survey 1:50k or 1:25k series.  Is this possible?  I have found a video for the fenix 5X (youtu.be/Y_n6LR4HJvQ) which at 7:28 shows that it can handle the 1:50k maps.  However, Garmin's support has advised me that the fenix 6 pro can't do this, with neither the fenix 5X nor the fenix 6 pro showing as being compatible devices on the relevant map purchase page on Garmin's website (in fact no Garmin watches show as being compatible with the maps).

Either this is a disappointing downgrade in capability or Garmin has changed the format of the maps such that the fenix 5X could use them but the fenix 6 pro cannot.  Can anybody clarify either way?

Also am I right in thinking the fenix 6 pro cannot offer map shading of relief?  This is a missing function for use during hillwalking (my main activity).  I also have a Garmin Edge 830 for cycling which can show shading even though it's actually less important for cycling than for hillwalking, arguably.

Many thanks for any pointers.

Ben