Thanks guys;
Interesting thing: This morning - just after I posted here, I did a Google search for 'iTunes for Windows', and found the link here:
https://support.apple.com/en-us/HT210384. The file 'iTunes64Setup.exe is for ver 12.11.3.17.
When I installed it on Windows 11 and opened the app, there was an update available, so I installed it. The update version is 12.12.3.5 - the same version I have on Windows 10.
I could not locate the setup file on my system, which wasn't surprising, as I had updated from within the app.
Now I have downloaded the file from the link provided by sveakul, and it is ver 12.12.3.5. Very confusing. One Apple site has a newer version than another?
When I went to the MS store in Windows 10, and entered 'itunes' into the search bar, it did come up with iTunes, but instead of the 'get' button, there was the 'open' button - since I already had the app installed.
When I switched to Win 11, I never even bothered to try the MS store; I just installed the (older) version I had found previously - and then ran the update.
So I may have reacted a bit too quickly on reading that iTunes was no longer available on the Windows store.
Now I have both versions saved to a backup drive, but I wonder how long Apple will allow music to be purchased and downloaded if they are trying to migrate to a streaming service (Apple Music?) exclusively.
I would rather not be at Apple's or Microsoft's mercy, so I will indeed check out bandcamp. I have tried Amazon, but I was not satisfied with the quality. That said, I would love to try some 24-bit 96KHz on my system to experiment with the quality.
I play music from MusicBee through a Schiit Modius DAC into a Schiit Magnius amp with Senn HD600 cans using balanced config. But I'm not so young anymore, so I kind of doubt I would be able to hear the difference between 16/44 and 24/96.
I have the same music on my Galaxy A51 (Android 11) phone and use HiFiMAN Deva Pro with their 'Bluemini' DAC/amp over BT LDAC when at home, but use a much less capable JBL/UA Train Wireless for running.