Hello. Have you tried the custom 24.10 ISO? Worked great for me on my T14s 64GB RAM, non-OLED. As far as I recall, I followed the step on the thread:
https://discourse.ubuntu.com/t/ubuntu-24-10-concept-snapdragon-x-elite/48800
You could then upgrade to 25.04 afterwards (I have not tried this myself yet).