I wonder why cloud vendors, even AWS, wouldn't invent a modern remote desktop protocol that works cross platform in easy way such as through ssh protocol that may perform at near native performance and they may just have a wider use case for cloud servers to increase their revenue. Of course it helps other vendors too but no one loses including the users.
AWS apparently has implemented something that works decently and cross platform, but AFAICT they're not sharing. The best docs I can find in a hurry are https://aws.amazon.com/workspaces/faqs/?nc=sn&loc=4 which talks about it not being RDP and only supporting connecting via their custom client.
