I have a freaking cool, useless idea, but i dunno if it will actually work

1. Put a usim in the slot
2. Reads information and connects with ISP
3. Turn on mobile data
4. Turn on hotspot
5. And useas a portable wifi

Don't ask me why you don't bring my phone, there are reasons

The os will be no screen only physical buttons with stripped down aosp

Can it work? Or in other words, is it possible?

If I understand it right, you're trying to make a mobile WiFi Hotspot? If that's what you wanna do, yes should be possible, there are already devices on the market that do that.

Sure. A Raspi, modem, switches on the I/Os, maybe a battery pack, there you go.

Then you may put a fileserver on it, or anything else you want.

I thought there are already small companies selling similiar devices, but I can't find any links right now.

I want to build a small device that runs a ripped off version of android that has the ability to read mobile data plans by connecting to isp and creating wifi hotspot.

Basically a phone with only hotspot features

Can anyone link some stuff selling in amazon which is cheaper than i want to make?

yes you can easily transform an old gsm into a full functional, highly advanced raspberry/arduino thing. root it, control/program it over usb port with console, once ur there, u can detach camera, screen, case, buttons etc.
Its free and needs less physical effort than connecting a real pi with a simbox etc... with all the protocols ready for 2018 internet communication

with the supernice advantage of having a week battery lifetime

Huawei sells devices that do exactly what you need :D

Just enter "huawei portable wifi" into a search engine of your choice :D

@D3add3d so insert a sim and make it a portabke wifi?

@CozyPlanes yup, you insert a 4G capable SIM into the device and it creates a WiFi AP and it has a battery that lasts 20+ hours.
One of my friends carries this thing around with her everywhere :D

@D3add3d fuckkkkkk

(This idea also came from a toilet)

@CozyPlanes but if you want to create it yourself I would take a look at ESP32 and "Digi XBee3 Cellular LTE CAT 1"

@amahlaka @D3add3d will do