Tablets: which planet (OS, manufacturer) can homemade devices be connected to?

Question

Do it yourself

The point is this. I need a tablet to which I could connect homemade devices. For example, via USB. Of course, you can force the device to connect via Wi-Fi, but I would not want to fence extra levels.
Data transfer must be two-way: the tablets display the incoming data and allow you to send commands.

Answer 1

Most modern tablets support USB OTG, which means a virtual COM port.
However, it is even more convenient to use a Bluetooth-UART module, such as the HC-05.