That was beautiful. Can I steal it for my grandpa's eulogy?

I do not need to be "educated". A computer is always personalised because you have your big box on a "monitor" wich in reality is a stripped down TV or you have a mobile computer called a Laptop. Calling a Smartphone a "computer" (🤣) is an "argument" of PC fanboys, who cannot handle the fact they are looking on a TV when they work, play, chat or whatever the fuck they do sorry. I do not own a computer and never will.

People use tablets, smartphones... because fewer people every year take their laptops with them. Sure they have less functions but they do not need more because they can do everything people need. Personally i do not know anyone owning a desktop PC anymore.

Of course computer can operate without operating system. OS is just a program (rather set of them) to use the computer. NES is just as much a computer as Commodore 64 or my mobile phone or the gaming PC my kids have or Switch. Yes, CD-i doesn't really classify as a console. 

Next he will say PC Engine is not a game console because it had 1 controller ports and/or has PC in the name (It's not a PC nor was PCFX)

NES is just as much of a computer as a gaming PC? A single purpose games console that has no OS (I looked it up) is just as much of a computer as a gaming PC? How exactly does a computer operate without an OS? They're called operating systems for a reason, you need them to operate the computer. Are you trying to say that just because the computer turns on when you press the button it is technically "operating" and therefore doesn't need the OS to be operated by the user? 

A PC has a BIOS. You need the BIOS to install an OS. A PC won't boot without a BIOS but will boot without an OS. People have gotten Windows 1.0 running on an NES. Some older consoles like that didn't use a custom CPU but an off-the-shelf one, made in the 1970s like the SEGA Genesis. Those CPUs were good for a long time. The Motorola 68000 was used in multiple consoles and computers from SEGA, Atari, Amiga, and computing devices in the 80s, and 90s.

Many computers in the past had no operating system. this was true for big commercial or research computers. They were designed to run a program directly from their input media, be it punch cards or tape. For convenience people started developing operating systems, as many function were made anew for each program. Also operating systems were needed if you wanted to have multiple users. So OS got developed. This culminated in Unix, a system consisting of a set of programs not just one that got circulated widely between research facilities, governmental computers and commercial computers.

Then later on with the home computer revolution you had again computers without operating systems. These were designs made cheaper so that you can buy them as a person, personal computers. Again the system was to run directly a program from the input media, here often cassette/datasette or floppy disks. Examples are Sinclair's ZX Spectrum or Commodore 64.

Even modern PCs are designed to run a program from disk, but nowadays the floppy disk is usually replaced with a hard-drive. Operating systems are loaded with this mechanism, as any program can be loaded this program can be an operating system. So you could still run modern PCs without an OS, it just will be difficult to find a program that runs without, you probably have to create it yourself.

So if you insist computers need an operating system you seem not to understand at all what a computer is.

Modern consoles all run an OS anyways. PS5 has a BSD based system, BSD being a classical Unix system. Xbox runs a modified Windows called Xbox systems software. Nintendo has developed their own microkernel for the Switch operating system. So according to his definition modern consoles all are PCs anyways, while old computers like C64 or ZX Spectrum that did not have an OS aren't.

Can you connect external controllers? Can you play on the TV without holding the whole console in your hands? Does it do split-screen multiplayer? Can you do it out of the box? Does it upscale the resolution?

Computer operates like the program you're using tells it to, doesn't matter if the program is operating system, a game or a spreadsheed app. On a technical level, computer is the circuitry required to do computing. Videogame consoles are a type of computers that are called videogame consoles because of the task they're designed to perform, which is to play videogames.