I empathize - I was a little worried about what would happen to my work if Observable shut down.

But the lock-in is less severe these days. The parser, runtime and standard lib are all open-source, so you can run a full notebook in VSCode https://marketplace.visualstudio.com/items?itemName=GordonSm...

I've come to appreciate the non-standard extensions they've made to JS too - the reactive cell model has greatly reduced the amount of code I've needed to write compared to a hypothetical React equivalent. It's my #1 platform for my small side projects these days.

I'll quickly note for anyone uncertain - Plot is pure JS so it doesn't have to be used in an Observable notebook. Will run anywhere D3 does.