Lightsail is basically a toy to compete with Vultr/DO/OVH/etc. You can't even rename a server or change its metadata. You can't resize a server (except for taking a snapshot and building a new server). Essentially, you can't make any changes to a server and there are zero tools for organizing, tagging, or even adding a description field. Of course, you cannot manage Lightsail instances using the AWS console (or even see them). All of the powerful AWS tools are invisible to you as well, and your entire Lightsail infrastructure is invisible from within AWS itself (except for the bill).
Lightsail is really great for personal sandbox servers, or for moving to AWS on the cheap, but it's not even as capable as its worst competitor (and certainly cuts out a lot of features compared to real AWS.)
The worst part is probably the surprising and seemingly minor factor of being able to simply rename or resize a server. This makes using it in a team or production environment surprisingly difficult.
With that all said, I still find Lightsail very useful for small prototyping and other fast jobs (or a Lambda replacement -- it's way cheaper than running any reasonably busy Lambda function), but I can't see using it for real production usage. Your best bet for real production usage, or something that will someday move into production, would be probably vultr/DO/linode. (OVH really wants to be great, and it should be because the hardware is really great, but the dashboard and billing are so bizarrely bad..)
AWS is good when you have a virtually unlimited budget or don't mind running up the bill while you're getting rolling, but getting locked into AWS will mean that you are stuck with it forever. It's very hard to migrate away if you start using a vendor-specific thing like DynamoDB (to be fair, Google Firebase has exactly the same issue; Instances are basically fungible, but proprietary data stores are not)