Unfortunately the BT Sport development teams were all disbanded last month and moved on to other work. The only updates to BT Sport apps on all platforms will now just be for essential fixes.
Also, the company that provides the player we use on PlayStation devices decided to go into liquidation in December, following the sudden death of their CEO. They didn't get to fix all the issues we had with it before this happened.
The only chance of Ultimate coming to PlayStation 5 will be if Discovery+ choose to offer it when they take over in summer - we don't yet know what their plans are.
Unfortunate timing all round.
Sorry that I couldn't bring better news.