I just discovered this and it works fantastically on any old / unused android device you might have lying around, I was shocked at how easy it was, all the instructions are there, once you have it running all you need to do is set your router DNS settings to your pihole IP address and presto! Ads and trackers are gone!
Not to take away from what you’re saying but old phones and laptops are very likely to have easily replaceable batteries as well.