What technology stack to take for the site admin?

Question

PHP

Good afternoon. Advise - what is the best technology stack to take to create the site admin panel.
Website - vafli-veresk.ru
Products are loaded via AJAX and taken from data.json.
You need to make a Personal Account to upload a photo and edit the text for it. And that's it!!
Therefore, I want to do it with minimal means ...
I don’t look towards CMS - I think that they are too heavy for this.
Ideally, data.json should simply be updated with data from the admin form and uploaded to the photos folder.
In general, I could do this on node.js, but the customer will not switch to VDS hosting for this.
Since I'm not strong in PHP, I'm looking towards some lightweight PHP framework. And in order not to get into mySQL, because I have no idea how to load data later via AJAX. You can consider storing data in mongoDB.
As options I see either native PHP or Slim PHP (is it easier through it and does it work with something like mongoDB? ..)

Answer 1

I absolutely saw somewhere on the Internet a service that acts as a backend for the data that you enter there. A sort of backend as a service. Unfortunately, I can't find it, but I think it would suit you.
UPD. Found. https://www.contentful.com/

Answer 2

Advise - what is the best technology stack to take to create the site admin panel.

Use the stack that you (or the programmer you hire) know best.

Answer 3

I don’t look in the direction of CMS - I think that they are too heavy for this.

Vsm, heavy? what kind of hosting do you have there?
Are you sure that you write faster than you would have done on the finished engine?