What is Dell Ubuntu Upgrade Policy?

Does anyone know what Dell's official policy is with regards to upgrades for Dell OEM installed Ubuntu? Do Dell have an official upgrade policy that provides some kind of official upgrade path to the next Ubuntu LTS version or am I stuck on 18.04 forever? If they do provide an upgrade path, how long is it likely to be before my machine drops off the end ?

I have just bought an XPS 13 7390 with a Dell OEM Ubuntu 18.04.3 (LTS) installed. It has a dependency on Dell proprietary device drivers.  Rather alarmingly I can see Dell have disabled distro upgrades by setting /etc/update-manager/release-upgrades to Never upgrade. With Ubuntu 20.04 just around the corner, I'm starting to wonder if I've wasted my money.

I bought this machine thinking it was compatible with the canonical Ubuntu release but if I try running the canonical iso from a USB stick the WiFi fails and the screen isn't FHD.

This machine was a lot of money and is an awesome spec - it would be nice to know that I am going to be able to keep it up to date. What is the official Dell Policy? It would be nice to know that Dell actually care and haven't just cobbled this together to sell and forget.