I’ve discovered https://gitpod.io/ a few months ago and prepared a Meteor starter project today, which is based on
meteor create, just with the additional stuff to run it successfully on Gitpod. Gitpod is an online IDE for Github/Gitlab/BitBucket projects, based on Eclipse Theia.
This is my repo with the additional files: https://github.com/fknipp/meteor-default
If you want to start the IDE to see the well-known Meteor welcome page, go straight to https://gitpod.io/#https://github.com/fknipp/meteor-default
IMO Gitpod is a perfect place for trials and demonstrations. I’d suggest to add Try it online links to the Meteor homepage, which open demo applications in Gitpod. By adding two files to the tutorials, it would also be possible to open the source code directly in the browser. So, there’s no need to install it locally anymore to get the first impression of Meteor.
MeteorPad was closed about four years ago. This could be some kind of successor.