Awesome!!!!
Some thoughts on the WoT part:
1. Enough users to follow the npubs behind most of the apps they're using
2. Where and how do you prompt users to follow those npubs?
3. There is no win-win for making users go through that step (and it might mess up their feeds etc) 
4. Follows don't have a cost and 90% of my follow-list will not know the first thing about trusting in software

Alternative idea 💡 : 
USERS:  Focus 💯 of the UX on letting them zap the apps they value. No ratings, no recommendations, no adding to "Following". 
BUILDERS:  Let them verify and vouch for each others apps. Build a Web of Trust amongst those who actually know how to verify (and what price to ask for it). 

Then you scan say things like: 
- Zapstore & 21 other apps (that you value and use) trust this app. Install?
- Here are the most valued apps in your network
- No other app trusts this app. Enter secret key / Read only?  

 Appreciate your thoughts and generally like the idea. I have a lot of questions though.

Zaps also require a WoT layer or it can be gamed.
Yes there are challenges with follows, but getting devs to vouch might be even more difficult. Will devs vouch, or apps, or the npub behind the app?

I think curators might solve this problem. Let's say Ben Carman (who anecdotally is linked to Mutiny, Harbor, etc) has a list of trusted apps. Curators could perhaps be found by WoT + zap weight.