Uibuilder: to subscribe or not to subscribe?

Some time ago there was a very nice discussion about a building a new dashboard. That discussion was initiated by @andrei-tatar, the author of the current AngularJs dashboard. Unfortunately the ideas from that duscussion have never resulted in a new dashboard. But I see that Andrei has mentioned also Svelte in that same discussion...

Another noob question: I assume we can never stick to a single language (Javascript) for all our tools (flow editor, backend, dashboard...) when we also want to have a native app for both Android and iOS?