It is a limitation of a PWA. A native app (wrapper) will likely be coming though, and a custom Capacitor plugin could theoretically interface with the native API to switch out icons. Theoretically. No promises though :)
Quoting this comment by the dev
So what you’re saying is Apple sucks at programming, so you want voyager to make an iOS app?
I’m didn’t say or imply either part of that, but I guess nice try on trying to put words in my mouth for some odd reason.