I'm a big fan of rendering majority on a server and then shipping it, especially with Phoenix's LiveView which allows you to write reactive UI without writing Javascript.
But I said it in another comment: shipping value beats everything. If you can ship quickly and effectively in JAMstack to lambda, don't let anyone tell you that's wrong.
Shipping value is important. If you can build a solution faster in a monolithic, MVC style framework running on EC2 instances, then do that. I think people get too bogged down in the minutiae up front and forget they are being paid to solve a problem ASAP. Worry about optimisations and improvements when its going to add more value than right up front when the burning need of the business is to have something - ANYTHING - up and running and helping generate revenue.
I'm a big fan of rendering majority on a server and then shipping it, especially with Phoenix's LiveView which allows you to write reactive UI without writing Javascript.
But I said it in another comment: shipping value beats everything. If you can ship quickly and effectively in JAMstack to lambda, don't let anyone tell you that's wrong.