Is it possible to container inside collection?
If not, is it planned to be supported?
It’s hard to make a custom card type UI.
There’s the “Custom Collection” that you can put a lot of things into, but can’t put a container inside. You can do a bit of customizing with just with that, but if you want more I think you have to rely on CSS (which is only available for business and enterprise level teams). Glide • CSS for Pages