I’ve made a first pass at a port of the arcade-timers extension to the micro:bit environment. You get the same functionality as in the MakeCode Arcade version in Blocks. As a bonus, I have exported the support functions so that you can use timer.clearInterval(), timer.clearTimeout(), timer.setInterval(), and timer.setTimeout() in JavaScript and Python just as their MakeCode Arcade counterparts.
Install the extension with this URL:
https://github.com/robo-technical-group/pxt-microbit-timers
Devs: Feel free to do a code review and submit pull requests. If you’d like me to transfer ownership of the repo so that you can use this to build an official extension, then just let me know.