I like the tab-switching behaviour in Chrome/Firefox and wanted Safari to have something similar. Another wish of mine was for it to be a web extension that feels native to the browser vs an app extension that looks out of place.
After waiting long enough, I decided to build one myself. A little preview of Tap Tab. The web extension APIs for managing tabs are pretty locked down in Safari, but I have already found a lot of value in using the extension. Some of the features that I find very useful(in the middle of building a few of these) :
Driven by keyboard shortcuts. I can see the tabs I have open at a glance and switch between them.
Fuzzy search to quickly filter down to the tab you want.
Quick switching between two tabs.
Ability to pin, mute, and close the tab right from the extension.
Say hello, and tell me what features you would like the extension to have!!