That’s not part of the current support article, so either that is wrong or you are thinking of something slightly different. They do offer an option for heart rate to drive TSS estimates at least.
But that is not the same as what is needed for AIFTP estimation from what I know right now.
It would take some notable extrapolation to take pure HR data and convert to some form of power estimation needed for FTP relationships. Considering the variability in the data, and things like road vs gravel vs MTB and such, any “power” data from that would be suspect IMO.
To a degree, that would be parallel to the PowerTap PowerCal HR strap they used to offer. I have one and it was interesting, but I wouldn’t consider it a great option when thinking about FTP estimation with any level of accuracy.