Is it possible to save a waveform from one sim into .qraw, then play that waveform in other sim with B-source or something else?

I don’t think there is a way to read a .qraw file directly from a PWL source. However, you can automate the export process using the .system command. This means you would run the first schematic to automatically export a .csv file, and then run a second schematic that uses PWL FILE to read that .csv file. This is likely the closest solution to what you are looking for.

Export to csv does not work properly? - QSPICE - Qorvo Tech Forum