Now, the app isn't as accessible as it could be, and that's just a matter of time, but one thing I tried to do from the outset was to put all its unnecessary bells and whistles behind a root-level CSS class, so folks who prefer standard web components can opt out of the frills.
Making a web app accessible takes more than that, but I intend to do more, down the road. Actually consulting with an a11y expert is something I'm willing to pursue. This is good stuff to know.
Another neat aspect of this project is, a ton of its text and information are just crammed into its HTML. The scripts do the bare minimum necessary to get the job done. This means web crawlers and other browserless web systems can glean lots of info from the app, even if it doesn't run.
I just took this a step further and made the Help popup appear when a visitor has scripts disabled, along with a bit of extra info just for them.