I have absolutely no evidence for this whatsoever but bear with me.
Altitude adaption is about producing more red blood cells, right?
Your body naturally produces red blood cells to maintain a certain proportion in relation to your blood plasma. Not sure on this point but I think that’s basically how you recover after donating blood.
One of the effects of heat adaption training is an increase in blood plasma volume.
So, if all these three things are correct, maybe you could get some kind of altitude adaptation by doing heat adaption training, sufficiently far in advance that your blood plasma volume increases and then your body has a chance to get the red cells back in balance?
Just a theory at this point.