I have a MacBook Pro, which hasn't been available with a matte display for ages. So I ordered a generic matte screen protector. If you wear a black t-shirt and sit in the shade, it's entirely possible to work outside.
Battery life can be greatly extended with decently sized external USB-C batteries.
And for pre USB-C Macs, HyperJuice made 100W batteries with some weird cable hacks to work with MagSafe Mac devices.
Also consider an external battery for your phone when using WiFi Hotspot when outside.