Historically Apple have not supported FLAC on their devices. I like I suspect quite a few people reading this was therefore very surprised to see it listed in the iPod Touch specs.
It would seem likely the FLAC support is due to the chipset of the iPod Touch supporting this format, as Apple use often the same chips other manufacturers use it is in hindsight not an impossibility. Furthermore relatively recently Apple updated the hardware of the iPod Touch i.e. June 2019. It could be that this is when FLAC support was added.
Interestingly the new iPhone 11 also lists FLAC support but the iPhone 11 Pro does not.
I would therefore say that Apple do appear to be adding FLAC hardware support to a number of their devices. I therefore expect that a future iTunes update may include support for FLAC.
For what it's worth over the weekend my Windows machine installed a new version of iTunes which added support for iOS 13. It is possible this along with iOS 13 may unlock FLAC support. I will have to check this at some point, first I need to get a FLAC file. :)
As an alternative solution consider the following.
- Windows 10 natively supports both FLAC and ALAC aka Apple Lossless including meta tags
- FLAC and ALAC both being lossless formats can be converted between each other with zero loss of quality and the embedded meta tags also get converted including any album artwork
- The file size of FLAC and ALAC is virtually identical and as they are both lossless as mentioned above the audio quality will also be identical
- You could therefore convert all your tracks to ALAC and still use them in Windows Media Player and then also be absolutely sure it will work in iTunes and on all Apple devices
I have for many years had all my music in ALAC and shared between iTunes and WMP. (I was the person who devised the original solution that allowed playing ALAC in WMP.)