Why Apple would need Xbox engineers to make their own console? They already have engineers who make smartphones, tablets, computers, laptops and even 'consoles' (Apple TV). And they are way more successful than Xbox. In fact, if they go to poach engineers why would they poach the 3rd one in the market instead of the market leaders?
Just because you have people who know how to develop a laptop doesn't mean those same people know how to develop a games console, c'mon. Besides it is about much more than just the hardware; API libraries are also important and those are often tailored to specific hardware implementations as well. Also it's rather foolish to think they should prioritize what engineers they get based on what the console has sold in the market; a console's sales are in no way dominantly dictated by how well-engineered or powerful it is. Otherwise many older systems would've been not only market leaders but been leaders in every single territory their system was in. That is very clearly not the case when looking at actual prior console generations.
Considering their experience with large-scale API libraries having cross-platform support between embedded systems (like Xbox consoles) PCs, and servers, and considering Apple are in those same segments while also desiring to leverage existing APIs and features tailored to an embedded systems design, it actually makes a lot of sense they'd want various Microsoft engineers to provide their talents in such an area.
If they put these smartphone/tablet 3rd party joycon-like controllers (Sony also patented similar ones with a small twist) to an iPad Mini they already have a console.
That's not how it works; you're
vastly oversimplifying the work that goes into creating a dedicated gaming system, as in something which vertically integrates hardware specifications, software specifications (API libraries, general code libraries, documentation, debug testing etc.) and more, into a static design whose specifications are set in stone for the next several years.
By your notion Sony could just take one of their random smartphones, pair it with a DualSense and viola! They have a new PlayStation Portable! Clearly wouldn't be the case now, would it?
I think the only thing Apple has to do is to make sure Unreal and Unity properly support their new APUs/OS making super easy and cheap to release any Unity/UE game on MacOS/iOS and to increase gamepad support/make a separate store for games that support gamepad.
That's only one side of the equation. You know as well as I that a "proper" console also needs to have features and content specific to its ecosystem in order to incentivize clients into that ecosystem and keep them there, which means major development investments from the platform holders.
Ensuring Unity/UE support their APUs and OS (BTW what incentives could Apple provide to ensure this for those engine owners beyond what they already provide?) would be the bare minimum thing for Apple to do.
Plus releasing their own gamepad that would be used on iPhone/iPad/Apple TV/Mac both as a normal pad and as a joycon attached to the sides of an iPhone or iPad.
This still does very little in and of itself, because either Apple would then need to retroactively add support for that controller to ALL of the games currently on their Apple Arcade platform, or they'd need to convince 3rd-party developers to do it themselves.
Either way, it would be a large undertaking and involve a lot of resources (and time) either way, they can't just simply release the controller and magically everything works with it.
Also, well this is more in general but, I don't see why people are underestimating Apple's ability to deliver a proper games console. I know the Pippin is a meme, but it was also 26 years ago, from a really bad spot in Apple's history. If they managed to turn around in general, what makes you think they couldn't do such with a video game system? They obviously have a lot more resources and experience since the '90s, and a lot more data on the market to have observed and learned from.
Given their brand power alone, I strongly doubt a new Apple gaming console would perform anywhere near as badly as the Pippin, and I think that scares some people. That said I think there are other reasons why they aren't seriously considering a dedicated gaming console: what could Apple address in terms of the gaming market that Sony, Microsoft and Nintendo aren't already addressing in one way or another? What can Apple provide that they can't, which benefits the market both for developers and for gamers? What value proposition in terms of content, pricing, and experience could Apple provide that the Big 3 cannot?
If they can't answer those questions clearly and concisely, then you're not going to get a dedicated gaming system from them. Period.