Yeah real hard to do. Its called an HDMI cable and you hook your computer up as a monitor. Wally World has em for about 12 bucks.
You can do that too, but that can be kind of annoying depending on what you want to do. Sound bleed was always what irritated me, you generally have one sound output so if you’re playing a game while your pumping stuff to your TV both sets of sound are coming out both places. DLNA sharing avoids that problem since the TV only gets what you’re sharing. Plus of course you need the PC and TV within cable distance of each other, which anything going over the network avoids.
It’s not hard to do - you hook up your TV as a monitor - but it’s much easier if it’s wireless so you can just sit there and summon it up. In addition, this has content that you may or may not have on your device.