You might want to keep in mind the regulations concerning camera manufacturers. When recording over a certain limit in time (which I believe is 30 minutes), the sellers of the camera pay an extra tax-amount - so longer recordings are usually reserved for more professional, expensive cameras.
What might be worth a try is recording with an external recorder ...
In my experience, that's a indicator of the line between consumer, pro-sumer and professional cameras. At a previous workplace, it was problematic enough to justify investing in a better camera for the situation that could handle longer video lengths.
Additionally, standard FPS for video are 24 or 30 fps.
You might be able to save some time on the card ...
Well, this hardly depends on what you want to do and need.
If you simply want to create cinematic images, 77D will be a lot better because of the bigger sensor.
If you need highly technical and sharp images, like I would expect it from a tech YT channel, I would take the iPhone X.
In the end, it matters more how you handle the camera, than what it can.
Well, you are asking for a lot of things here.
I'd guess the best option would be a Canon M50, it is not a DSLR camera, but the industry tends away from DSLRs anyway.
It can shoot good 4k footage, is new and also shoots good images. You can get it with a double lens kit for around 900$. You can also adapt it to Canon EF.
She has Connectivity to your phone ...