I now have a working zpool auto-switcher:

https://gitlab.com/salfter/zpool-switch

A note of caution: the description of their API is pretty much non-existent, and the normalized-profit statistic they report isn't in the same units from one algorithm to the next (it's BTC/day per MH/s for most, per GH/s for several, per PH/s for sha256d, and per kS/s for ethash).  Based on the data I've seen elsewhere, I think I have the right correction factors to correct all of them to BTC/day per GH/s, which matches up with the hashrates (in GH/s) in my miner configuration file.  If you notice that a particular algorithm seems high or low by some multiple of 3 orders of magnitude, let me know.

Further development of my auto-switchers will be under Gentoo instead of nvOC, but they should still work under nvOC with no changes to the Python code and just binary path updates in miners.json to reflect the different miner locations (the miner binaries live under /usr/bin on Gentoo).  Also, the shipping miners.json refers to a miner (at https://github.com/krnlx/ccminer-xevan) that nvOC doesn't currently provide.  Blake2S can be reconfigured to use tpruvot's ccminer at a minor performance hit.  XEvan is a relatively new algorithm only supported by the aforementioned ccminer-xevan; as a fork of ccminer, it should be relatively simple to get running under nvOC if desired.