[HarHarVeryFunny]

Does the concept of O -ve as a universal donor type apply at all outside of the ABO group, and am I understanding correctly from your comment that even within the APO group O -ve compatibility would still be subject to this antigen matching?

Don't we have synthetic blood, at least capable of transporting oxygen ?

[kadoban]

There's not really a synthetic oxygen-carrying blood substitute that's commonly used. Turns out it's actually pretty hard to get right. https://en.wikipedia.org/wiki/Blood_substitute has some info on different approaches and products that were/are sometimes used, but the short story is: not really.