Thank you for the pointers to external resources.
I’m well aware that this is a lost cause, but the whole point of the exercise was for me to run a low-power device around the clock with internet connectivity and a USB port for my NEWPAC miner. This is just a miner for luck, with intergalactically small odds of mining any block ever.
I knew all that when I was getting into this.
But I was getting nowhere with OpenWRT and so I wrote this question in the forum before giving up and throwing everything away. You took the time to respond and I’m thankful for that.
So I shall try. And it will be wasted time. And that is OK.