Is 400 lumens enough for daytime viewing?

No. At 400 lumens the picture washes out with daylight or room lights on. It looks best in a dark or heavily dimmed room, especially at larger image sizes.

Does it really output 1080p?

Yes, the panel is native 1920 x 1080, so it does not upscale a lower-resolution image. Feed it a 1080p source to get the most from it.

How big a picture can I get?

The image ranges from 50 to 300 inches diagonally. Practical brightness drops as you go bigger, so most rooms will be happiest in the 80 to 120 inch range.

Can I stream without a laptop or stick?

It has Wi-Fi 6 and Bluetooth 5.2, plus HDMI and USB inputs. You can cast or connect wirelessly, but a streaming stick over HDMI is often simpler for apps.

Can I connect a soundbar or headphones?

Yes. Bluetooth 5.2 lets you pair a speaker or soundbar, and there is a 3.5mm jack for wired headphones or speakers.

How does it compare with brighter 1080p projectors?

Brighter rivals give a more usable picture with some ambient light and often better contrast. This one wins on size, weight and built-in wireless at the cost of light output.