I tried but seems aws has closed the door. To connect ec2 to Lightsail via private IP I have to create a "ec2-classic VPC" in ec2. But aws has disabled "ec2-classic VPC" in all regions
This pricing only seems make sense when the two instances are belong to different owners that are billed $0.01/GB both. But still ridiculous: Data transfer in from internet is free, but from another zones/regions cost $0.01. Maybe they just want to make the pricing "look cheaper"?
Installed, and uninstalled when I found it automatically add it's icon to my dock. (It's the first mac software I ever installed that add it's icon to dock itself)