I've worked with typefaces forever and had to meet ADA requirements for printed publications in a former job.
The "old" rule of thumb is that a body font with serifs is easier to read because it helps a reader follow a line. Major news organizations still use a serif body type on the web including ones associated with video such as ABC.
But When I read about accessible fonts, every one listed is sans serif. For the dyslexic reader, advisors are concerned about the consistency for font strokes which means their selected lettering also falls into the sans serif camp.
I'm currently in redesign for a website to switch to Squarespace 7.1. It includes many long-read articles so the body text selection is critical. I'm also being consulted on a print project for an entity that is extremely concerned that it makes all of its resources accessible.
Thanks for any guidance you might have