OK. I got some good news and some bad news.
Bad news, it's not available via the playstore for some reason and straight sideloading it doesn't work. It just doesn't install.
Good news, I got it installed on the T5 and it's working fine, but the process is a little more tricky. It does work though. It may work the U1 as well.
Go to
https://apk.support/download-app/com.disney.disneyplus
Set device to TV, android to 9.0 and click generate download link.
Download the three apks that were generated
(base and two config apks).
Note: You will most likely need to change the settings for the U1. Set device to Tablet, android to 5.1 and click generate download link.
Now download SAI (Split Apk Installer) and install it.
https://apk.support/download-app/com.aefyr.sai/1569816000_vs-2.8
Open SAI, select install APKs and select the three apks you downloaded (base and two config apks).
Enjoy Disney+