The charger itself is going to be smaller/cooler, but it will have no impact on the way the device is charged. The way phone heats up or not is entirely on the phone's side.
The OnePlusZ looks like a low-end OnePlus phone. Xiaomi announced the Mi Note 10 today which will likely be the best mid-ranger, as it looks great and its predecessors were the best selling mid-rangers (globally).
As for displays, a high refresh rate doesn't cost anything on LCD or OLED and is easy to implement. Display manufacturer's BOM might be an extra $2 or so for a faster controller and that's pretty much all that is needed.
There are only two reasons why high refresh rate screens are still not the default:
1. It taxes other hardware and is still impractical on battery-powered devices - the smaller the device is the worse of an idea it is as the smaller battery has to withstand a larger portion of the significantly increased GPU/CPU demand.
2. It requires a fast interface between the GPU and the screen. One of the reasons 4K monitors are 60hz is just because a higher refresh rate at that resolutions requires HDMI 2.1 or DisplayPort 1.4 which are new, fairly rare, and more expensive. Devices like laptops and phones also have such interfaces which are typically much slower to save costs and energy.
The OnePlusZ looks like a low-end OnePlus phone. Xiaomi announced the Mi Note 10 today which will likely be the best mid-ranger, as it looks great and its predecessors were the best selling mid-rangers (globally).
As for displays, a high refresh rate doesn't cost anything on LCD or OLED and is easy to implement. Display manufacturer's BOM might be an extra $2 or so for a faster controller and that's pretty much all that is needed.
There are only two reasons why high refresh rate screens are still not the default:
1. It taxes other hardware and is still impractical on battery-powered devices - the smaller the device is the worse of an idea it is as the smaller battery has to withstand a larger portion of the significantly increased GPU/CPU demand.
2. It requires a fast interface between the GPU and the screen. One of the reasons 4K monitors are 60hz is just because a higher refresh rate at that resolutions requires HDMI 2.1 or DisplayPort 1.4 which are new, fairly rare, and more expensive. Devices like laptops and phones also have such interfaces which are typically much slower to save costs and energy.
Good to know on the screen refresh tech. I thought it would be a bit more complicated than just a part having a few dollars premium. But I get the part about battery consumption and have read about the effects of high refresh rates on that. I think it was the Razer phone from a year or two ago that had one at 90 or 120? And it was the highlight of the phone but after seeing the S20's issues, it looks like OnePlus's 90 hz is good enough for anyone wanting to go beyond 60.
About the SE, Tim Cook just came out and said what most of us knew about the SE's goal: https://9to5mac.com/2020/04/30/tim-cook-iphone-se-android-switchers/
One more video you'll definitely like is this Indian tech reviewer talking about fanboyism ruining brands in the long run. He doesn't mention Samsung but he does mention two brands you're still more familiar with than I am with Sony and Xiaomi and could still probably be applied to Samsung, as well as any other brand: