Looking for a secure PRNG that I can implement in hardware
First, you should not write your own CSPRNG - there are plenty of well vetted ones from which you may pick.

Second, your text and your pseudo code do not match (rotate key or rotate the seed).

Third, as I understand this algorithm it doesn't even give good randomness properties.  For example:

Main&gt; let seed = `0x82398eeaf74239 : [64]
Main&gt; let key =  `0x8732754279249  : [64]
Main&gt; let out = take `{256} (prng key seed)
Main&gt; out
0x5555555555555555555555555555555555555555555555555555555555555555