Hello, I've read your pdf attatchment in detail and very interesting on your job.
I have experienced Cryptocurrency Trading site, so I was easily understand your proposal.
I can implement both of your User/Shop owner app and Admin panel.
Also I've good experience with Paypal payment.
About implementation framework, please suggest as your want: PHP/Node/Mysql/MongoDB, ...
About mobile version, I suggest React Native.
So please tell me your design idea, then I can start working soon.
To more good understand, please check my past works on profile : https://www.freelancer.com/u/RyuMaster
I like long term relationship, and providing pixel-perfect results.
I want to hear from you about more details.
Thanks.
From Konstantin~