I've had a tab open for this for months, and I finally decided to look through it. Found a link to this site that can audit/analyze websites for both mobile and desktop. I ran it on whydrs.org and saw some potential areas for improvement.

Linking to the mobile and desktop tests below. It includes some steps for remediation, though it does seem pretty technical.
https://pagespeed.web.dev/analysis/https-whydrs-org/m07b7fbhgj?form_factor=mobile
https://pagespeed.web.dev/analysis/https-whydrs-org/m07b7fbhgj?form_factor=desktop