Posting, to me, is sending a photo to a hosting website that gives you a link that DU uses to display the photo, or perhaps sharing it with others so you don't have to email photos to them. This is great for very large photos.
So that is what I address, and the post in the photos forum addresses.
Now, as for sharing with your computer, I go Apple to Apple, so that's the Image Capture app and a cable or AirDrop. But with Windows, what I have done in the past to help friends is to buy them a copy of PhotoSync app (not expensive but the appstore won't show me the price of something I already bought.). The desktop companion app is free (Mac/Win10) and it transfers between everything. Windows, Mac, iPad/iPhone, Android.
Not a sales pitch. It just works for me when I need to transfer between different makes.
There may be others.
However, I regularly post pix to DU from the phone, ipad and desktop using one of those web-based photo hosts all the time.
You can put iphone photos in icloud (limited space is free) and access them via logging into iCloud over the web, on anything, if you enabled web access to photos in your iCloud settings. There is an "iCloud for Windows" but I have no experience with it.
https://support.apple.com/guide/icloud-windows/set-up-icloud-for-windows-icwee190673a/1.0/icloud/1.0
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