Not all applications on your computer may be encrypting their packet traffic properly, though. That goes especially for the applications that might be trying to reach out for resources on your local home network (like printers, file shares, and other home servers) as well as DNS requests which are usually still made in the open. I would not recommend eschewing an entire security layer willy-nilly like that. On public Wi-Fi, I would definitely still suggest either a VPN or using your cell phone as a tether or secure hotspot instead if possible.
Sure, but it’s also like, if you’re stepping away from your laptop for a few minutes should you lock the screen or shut it down completely.
The most secure option is to shut it down completely, but also it’s fine to just lock your screen.
If you’ve already got a VPN and it’s as easy as locking your screen to enable, go for it, use it. But if you don’t, you don’t need to go out and get one. You’ll generally be ok without one.
I mean, technically - the most secure option is irrevocably destroying the laptop everytime you have a break.