Thanks for looping me in 
My 2 cents on this
I’m personally a fan of using frameworks over reinventing the wheel, unless it’s strictly necessary or the product requires really new technology, so for me having a framework that allows to go custom when necessary is usually a good choice.
Specifically for OFN, I consider the admin side as a functional tool, where efficiency and ease of use are primary. It’s a table-based software, and I guess it’s going to stay like that in the future.
Neither bootstrap nor foundation have advanced table patterns. I spent a bit of time looking at separate libraries for table mgmt but couldn’t find anything as advanced as vuetify. What I like about it is that is based on Material Design, which is a design system with some solid thinking behind it, and a huge user base, familiar with its components and look and feel. And obviously, given the website has a massive amount of interactive examples, it makes it easier for a contributor to explore its modules, play with them and assess which are more suitable. Mobile is extremely well supported too.
I guess Vuetify can only be used with vue.js. Not sure if stack decisions should be driven by a UI framework though ahah.
I can do a proper analysis spike on different frameworks for us to assess them properly, if needed.
For the front shop website, I am not entirely sure. Thinking out lout, I’m a bit worried that adopting a framework might limit the potential to explore ways of designing the most appropriate interface for the final users, and result in just a bunch of components assembled together, and less of a cohesive experience.
But I’m not too familiar with it, Yuko is definitely the best person to provide inputs to that.
One question I have is internationalization, alphabets support and overall accessibility and inclusion. As OFN grows, hopefully we’ll be able to support a even more diverse range of people, with different needs, languages and ways of using technology, so finding a framework that has good foundations for that might be relevant.