It seems like there’s a lot of ways to go about this that may be overkill, so I’m curious which may avoid that.
Low maintenance in this context is aiming for moderate technical knowledge/setup, lower cost, and portability in case you need to migrate your site and so minimal hassle in that process.
ECS would also incur either Fargate or ECS, and S3 + Cloudfront, while robust is definitely not very simple. I’m not saying it is hard, just complex.
Your Github / Gitlab Pages solution is a great idea… even if you want to use custom domain. They both support it.