I wonder if they had to build the new Gateway Load Balancer in their implementation of this, so they decided to turn it into a product as well.
Azure internal load balancers have some hang ups, but load balancing egress or east-west traffic across security appliances in AWS has always been diabolical in comparison.
I've never used the Geneve protocol, so I can't really tell if this is going to affect which vendors can use the GWLB.