[asab]

Firefox can screenshot the whole page - it's built in. I believe it can be done in headless as well.

https://support.mozilla.org/en-US/kb/firefox-screenshots

[Nux]

Can it screenshot lazy loading pages?

[williamdclt]

I think it can be smart-ish about this (scrolling for you, but maybe I'm thinking about an extension). I've never found anything that handles virtualised lists/tables though, like screenshotting an entire Slack thread