Why doesn't Firefox dynamically update the site and why is YouTube sharing not available?

Question

Mozilla Firefox

Hello. I have a question. Or rather two.
For example, on an online store site in Chrome, when I select options, the Browser page does not reload entirely, but an animation appears and the content reloads. Firefox, on the other hand, displays an animation and then reloads the entire page.

Second second. In Chrome, Vivaldi, Edge, etc., when I look at YouTube on my laptop, that is, the window in the player is to rummage through the view on another device. Firefox doesn't have this.

Can this be fixed?