I would start with something simple, like i2c or i2s dac, or classical parallel r2r dac, and see where that leads.
Maybe you should have a separate step for dac that only accepts either a parallel or serial data stream in a specific format, and then have separate steps that do the data transformation needed to shift whatever is coming in (can, i2s, ...) into the format the dac requires. Essentially:

1. dac block: supports parallel input of 1-n bytes, allows averaging of subsequent values (averaging 8 values on 1-bit input = 8-bit serial dac)
2. logic manipulation blocks:

• data extraction from fields given a packet format description
• ability to split and merge fields
• bit and byte permutation
• be able to run a bit permutation over a series of bytes, eg a full field
• ability to run byte permutation over a field

those two, followed possibly by a fir, should be a good start for having a virtual dac.