Custom Integration App for a folder where I have only Upload access

Hi,

I need to create an app which will be able to access folders which are shared to me with Upload only permissions.

With a developer token I can simply query for all items in my root folder, find necessary folder there and upload files to it - and this works fine with the shared folder, where I have Upload only permission. However, developer token is temporary while I need to give my app permanent access to my files. How can I achieve this?

I found that custom app integrations only work with Download permissions or All permissions provided which is not my case (or is there a possibility to work with Upload only permissions?)

I also tried to create an app which has JWT access to my enterprise. However, after initializing a client with JWTAuth  instance I can only upload and download files to/from app's folder, while I need to access my (admin's) content. Is it possible with JWT access?

Thanks