I can't access my iPhone's internal storage?

Have you tried an iMac? You can get one used if you haven't and don't want to "get too far in".

iMac now has Siri and automatically accesses iCloud things (including the iPhone's things). once you try this my feeling is you'll forget all about the idea of putting files on windows 10.

on the other hand if your trying to use iPhone as a memory stick my advice is don't: just buy a small memory stick

you can use iCloud to store files from iPhone or iMac. i'm unsure if Windows 10 can access iCloud - have to ask someone else.

QuietMacFan wrote:

Have you tried an iMac? You can get one used if you haven't and don't want to "get too far in".

It's still an expensive solution to a problem the can probably be easily resolved, for free, with a little help and support.

The only access that as ever been allowed directly from a computer (i.e., not through iTunes) was ability to import photos from the phone to the computer.

Read this

Import photos and videos from your iPhone, iPad, or iPod touch - Apple Support

Regards

Giulio

The following may also help: If you can't import photos from your iPhone, iPad, or iPod touch to your computer - Apple Support