Downvote for actually suggesting turning us back into 90s era "Best Viewed In" situation.
I do applaud the wanting to improve performance elsewhere, but still gets a big shake of my head in disappointment that dev is allowed to get to a place where it only works in one browser at first until some amount of work after release to fix to work in other browsers. My sincere hope that you do get it to work universally, realize what was done that made it one-sided to begin with, and avoid those things in any future projects.
To be honest I don't see this as such a bad thing. Google Chrome has 70% of the browser market share, while Safari has 4%. I don't think there's anything wrong with prioritizing more popular platforms, specially when you just want to ship a project that you worked on in your spare time to learn new things.
What evidence is there that anything Chrome specific was used? Safari’s WebGL support has come later than others, and there are reports of WebGL being slower on Safari than Chrome, for example https://developer.apple.com/forums/thread/696821 It’s possible your incredulity maybe should be directed towards Safari and not someone trying to do their best?
Despite using firefox and wantind cross browser projects I think the learning involved in browser compatibility is a LOT less interesting then about the math behind animation.