Safari speed reading extension

Hi everyone, after (finally) upgrading to Big Sur I’ve decided not to use Chrome/Brave and instead be fully invested in Safari. So far, it’s going good, and I’ve mostly been able to find alternatives extensions to those I used on Chrome.

However, I have not been able to find a speed-reading extension. I know that Instapaper has something built-in, though I don’t use it, and as far as I understand the free version is limited.

Does anyone here know of any good speed-reading extensions for Safari 14.2 (on Big Sur)?