RF Communication between two ATtiny85

Hi, first post here so I'll appreciate the help

I want to create a communication between two ATtiny85 using simple 433/315MHz breakouts.

Because I passed quite a long way in this, I'll describe everything I already tried:

First I programmed with RadioHead library but it did not compile on ATtiny, apparently it is not compatible.

Went on searching the internet for solution and found 'Manchester' library which seems to be working on ATtiny. From what I have seen the guides online only show a ATtiny transmitter, not receiver. And indeed, when tried using Arduino UNOs everything works. When trying with ATtiny, only the Tx side works.

Another lead was the internal oscillator. Some say it is not accurately tuned and so communication protocols can sometimes not work. So I turned to 'Tiny Tuner' and tuned the ATtiny oscillator (using OSCCAL register), although it was already about +-1% off, now it was spot-on. Still, Manchester library did not work for the receiver.

Next step was a blog page that mentioned a solution of deleting some .cpp and .h files from the RadioHead library and that will make the code compile. Did not work as well...

As suggested in many forum posts, I tried different (mainly slow) baud rates, around 1200. That didn't help.
Some of the comments in forum posts suggested different I/O behave differently, so I changed I/O and that did not help either.
Worked with Digispark clone and with DIP8 ATtiny85 chip (barebone)

Anyone with experience in making this work?