I realize that #activitypub is an open standard, but focusing so much on Mastodon right now as the only way to experience that seems kind of bad. Are there viable alternatives to Mastodon right now with a full web interface and functionality?
Should we start working on a high performance #rustlang implementation now so there is more than one choice of stack?
Keep in mind that ActivityPub is versatile, so a Mastodon/Twitter-like experience is only one use for it. Anything from RSS feeds to music players can participate in ActivityPub.