If you want to use it on the beach you will probably need an e-ink display because no laptop screen can compete with the sun. But matte is still infinitely better than glossy for less than ideal conditions such as working on a train where there might be sunlight coming in from the side.

Glossy screens are, in my humble opinion, a stupid gimmick because they look a bit better at ideal viewing conditions. For mobile devices the viewing conditions are most often not ideal, so it really doesn't make any sense unless the screen has to be a touch screen. I have had one laptop with a glossy screen and I ended up putting a glare reducing sticker on it because the glare was intolerable.

Based on my experience with the System 76 Lemur Pro coming from a Macbook Pro, matte helps a bit. You won't have mirror glare like on the Macbook, but the sun will still wash out the matte screen.