I work at a place running a million containers deployed in all 3 (Azure, AWS, GCP). I can assure you they are radically different; autoscaling works differently, the load balancers work differently, the networking infrastructure is completely different, the failure modes and limits behaviors are different, the instances perform differently, observability is different, and they all suck in unique and different ways that we discover on a daily basis. Shit even AWS can't keep their regions consistent; each region has different products and features and they fail in different ways.

If you are the one maintaining it it's a full time job handling all these edge cases, it's completely miserable and I wouldn't recommend it to anyone.