Hi @urassari,
Interesting challenge, but could you please be a little more specific about “without serial” and why?
I was about to suggest Bluetooth, but that is strictly speaking, if I understand correctly, also serial(UART) over Bluetooth for sending text to the micro:bit:
UARTService - micro:bit runtime Video Demonstration
I am, coincidentally, on an overlapping journey myself, looking at different ways to connect the micro:bit to a computer and/or MakeCode Arcade. Just now I was searching for a way to communicate(send e.g. text to micro:bit) via the simpler radio/gazelle protocol, but have not found it yet and starting to doubt this would work on other Bluetooth radio devices than the nRFs(?).
Here is an interesting project making the micro:bit a generic I/O device, but it has custom firmware and abandons MakeCode:
But if you want a much better answer, you should try and hope to get in touch with the experts in this field on the forum, like @bsiever.