Seems much more convenient than diving into dev tools every time you want to quickly check an element’s property. 30/month is a bit excessive for just that one function.
I think the same person makes CSS Scan ($95 lifetime): https://getcssscan.com/
Add an event listener on the entire document.body
Get the event.target and the style and then descend to the children. Put it formatted in the clipboard.
Then do it as a bookmarklet and deregister the click handler when you're done so you can continue interacting with the site
It's probably around 12 lines of modern js.
You can add a fancy graphical outline to know what you're selecting with a few more lines. Just make sure you draw it on top and don't modify the elements. Use a css filter to make it work on all elements.
Modern tooling is pretty great.