MikolMelamdai,
“I need one that supports 4G (because 2g and 3g are not supported at least by some of the carriers), preferably with a qwerty keyboard (though I know that�s hard to find), with hotspot capabilities but with a way to block internet on the actual device.”
It might be worth taking a look at the Light Phone II. It is a niche style tiny E–Ink device with a touchscreen (QWERTY keyboard). It is 4G, can make a hotspot, and has no browser at all. It can call, SMS/MMS (images don‘t show up on the phone but can be forwarded to email), play music and podcasts, clock alarm, calculator, a directions tool, and recently a calendar. To my mind that‘s almost the perfect set of tools I want in a phone (if only it had a camera and flashlight I‘d shout its praise from the rooftops).
The downsides of the device are the the janky refreshing screen that all E–Ink devices share by necessity, a bit slower touch responsiveness than people are used to with a smartphone, a small battery that drains quickly when reception is poor or using directions, and a rather high price compared to other dumbphones (it‘s a small company and the target customer seems to be the Yuppy millennial who realizes how harmful smartphone addiction can be but still likes tech). Still much cheaper than a new IPhone or high end Android smartphone. The software is LightOS, which is a fork of Android.