Your going to get both sides. Get an Xbox or get a Playstation or whatever they are called now. If you want my opinion (Older Gamer 46) build a PC with him.

That's bonding and he will love it. A bit spendy depending on what kind of rig you build but if money isn't too much of an option I recommend PC. A good resource is reddit buildapc and buildapcsales.

If it has to be a console my buddy says Xbox all day if that matters.

There are many potential options. While I'm personally partial to the gaming PC due to the versatility and additional functionality I have at my disposal, it is not a simple thing to use as it requires technical setup. While the setup's not that complicated, for someone with no tech background it would be overwhelming.

First important part to note is if he already has spent time playing video games, and if he already owns a system. He likely is much more well versed, even at 10 years old, than you are at the various gaming systems. It would be best to speak to him regarding it and he can help likely more than we can. If he truly has never had any experience regarding video games, likely due to family not valuing such devices, your best bet would be to go for the Nintendo Switch. The games tend to be fairly low in graphic violence and are "family friendly" by design.

For the more serious gamer you're looking at Playstation 4 and Xbox One. There are differences, but in this generation, the playstation 4 won the console war and is definitely the better system of the two. The selection of games is significantly larger than the switch, and can also more violent or graphic than will be found generally among the nintendo selection, assuming that such things are important to you or your grandsons parents.

Games for playstation 4 that are single player, and he can enjoy apart from yourself are Horizon Zero dawn: A post apocalyptic world filled with robotic dinosaurs. You kill a few evil humans, but most of the fighting revolves fighting these robot dinosaurs. Spiderman was also a pleasant game that my youngest brother enjoyed before he died, I just got my PS4 back from the police following the investigation, and hope to enjoy it as he did soon. There are other games, but as I prefer PC gaming, my exact knowledge is limited.

Unless you go with the PC route you'll have to pay a monthly or yearly subscription fee for online play to play with eachother from your own console. If you do not want to pay such a fee, I also believe Nintendo switch would be best as I'm under the impression that it has a wider selection of split-screen gameplay compared to the other two variants. This will allow you two to play games together, in the same room, with or against eachother. Some games have co-operative gameplay, others adversarial. Most racing games, for example, are adversarial by their nature.

Summary: All things considered, I'd recommend the switch more than most others unless there is an interest in serious gaming.

The most popular are

Playstation 4 - if you want a console. You can switch the hard drive to a bigger one on the 3 so i imagine it might be the same for the 4. This has a mix of kids and teen geared games when he grows into that

Nintendo Switch - if you want a portable. Nice big screen and has plenty of kids games.

PC - can play games, but would need the most monitoring as a parent. Can switch parts out to extend shelf life, improve graphics, or improve performance.

Nintendo Switch and Mario kart , and super Mario odyssey don’t get the switch lite. The switch lite is smaller and doesn’t hook up to a tv.

THANK YOU SO MUCH PEDES FOR ALL YOUR ADVICE!

PS4 is something he can grow into with a good library of games. Nintendo switch is very kid friendly with games geared towards beginners. This console cycle is about to end, though. New consoles are coming out in the winter months. You might want to hold off and get the newest when they come.