AA Compliance for Complex UI

Hello W3 Community,

I am part of a project that is trying to achieve Level AA WCAG compliance
and has complex UI's including large data tables, embedded PDFs, and a
scrollable timeline (similar to https://www.tiki-toki.com/). We did not
start with mobile-first designs and are experiencing issues trying to meet
the AA requirements (specifically *'SC 1.4.10 Reflow'*).

Wondering if anyone has dealt with trying to fit a complex UI in a screen
equivalent to 320px wide or can provide some web examples?

Looking forward to your feedback,

Sabrina