You are talking about the best OH in the world rn. yes there are Cristina and Fedorovtseva but they are different types of OH. You won't find that complete OH as Gabi.
There are 3 other OPPs at the same level as Haak or better than Haak, and there are also OPPs close to Haak's level such as Akimova, Antropova stysiak and Jordan.
Akimova and Antropova are not close to Haaks level atm. They might be in the future, perhaps in 2-3 years, but not right now. Antropova is averaging 40% and Haak 51% in the Italian league right now and in previous season Antropova had 42% and Haak 47%. Antropova is athletic and moves well for someone her size, but she usually struggles vs taller blocks and triple blocks. Akimova has great stats or numbers, but her performances against better oppositions so far have been underwhelming. I agree about Stysiak and Jordan Thompson, though. Stysiak is an exceptional player, but most importantly she is also rising to the occasion and do not crumble vs strong teams.