The way the Microsoft Store on Windows 10 has handled Edge extensions, finding what you're looking for hasn't been the most elegant experience. While extensions are collected in one spot, accessible from the Store's front page, their grouped together with no category distinctions. However, it looks like Microsoft is gearing up to make that experience a little more organized.
With the latest update to the Microsoft Store on Windows 10, has added a dedicated "Edge Extensions" tab for at least some users. It's unclear at the moment if this is an A/B test or just a slow rollout; so far, we've only spotted it on one machine running a non-Insider Windows 10 build. However, for those who have it, the tab appears along with the other categories at the top of the Store, just to the right of the "Books" tab.
Along with a new tab, the Edge Extensions page itself has received an overhaul. While it previously lumped available extensions together, the new page is broken up into categories, including: Recent, Adblockers, Password Managers, Productivity, Shopping, Social and entertainment, and For developers. While categories would have been handy before, it's likely Microsoft is making the move now because it has enough extensions to actually fill out the page for each category. It's a small change in the grand scheme of things, but the new section should make browsing for extensions a little more convenient.
To check out the Edge Extensions tab, you'll want to make sure your Store app is updated to version 11802.1001.8.0. However, be aware that, whether it's because of a slow rollout or an A/B test, it isn't available to everyone just yet.
Thanks to @asmitde for the tip!