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?