You can't¹. There is a new browser called Orion² currently in private beta that uses the same engine as Safari, which you can use Firefox and Chrome extensions

You can't¹. There is a new browser called Orion² currently in private beta that uses the same engine as Safari, which you can use Firefox and Chrome extensions on. It works both on Mac, and surprisingly on iOS. I believe it's the only browser on iOS that allows you to use -some- desktop extensions. I use uBlock Origin with it on iOS and it works good enough. ¹ https://github.com/el1t/uBlock-Safari/issues/158 https://github.com/el1t/uBlock-Safari/issues/158 ² https://browser.kagi.com/ https://browser.kagi.com/