Me too, with help from Tom.
I used the referenced procedure for an iPhone13 and an iPad Air 3 and it worked fine on a Windows Laptop with an Intel Blueteooth Adapter, but not on a Realtek one. My trials and solution are in that linked thread for anyone who stumbles across this thread.
My question relates to older iPads; I have an iPad 4 and that did not work on my Intel Adapter at all, it gave the same “IRK-free” information in the registry as my failed attempts. Has anyone tried the Windows method with older iOS devices?
[EDIT ] Fixed it myself, see here.