Need input; I just made my own harissa and I have liquid leftover from soaking dried peppers.

i have made mexican sauces using dried peppers and have noticed sometimes the sauce has an underlying bitterness. i asked a mexican chef you tuber and she said not to use too much of the liquid used in soaking the peppers. i tried that and next batch of sauce was not bitter. or....it could have been the peppers. i would taste the liquid used for soaking the peppers and decide after that. it does seem a shame to throw it if it doesn't contain off flavors. maybe, freeze in ice cube tray and use for braising, gravies, sauces etc too.

Your ideas sound fine. Or throw it in the freezer to use later. Could also be part of a soup or sauce.