Some do for chrome on android. They have to be named, you can search for the same in omnibar and tap. Works for things like changing playback speed.

Bookmarklets can work in mobile browsers.

For mobile Chrome:

- Create a new bookmark

- Replace the bookmarked link with the bookmarklet javaScript code, e.g., javascript:alert('hello world')

- To use the bookmarklet, start typing the bookmark name in the address bar until the auto-complete displays the bookmark, and then click on it.

For mobile Safari,

- Create a new bookmark and replace the URL with your javaScript code

- To use the bookmarklet, tap on the bookmarklet name from the bookmarks menu

(The edit was to better format my comment)

Hey this is too cool. Thank you