I discarded some other options, for example reporting time manually each week or each day.
Another discarded idea, that’s free to implement: you can achieve the same result with just Shortcuts app on iOS. One tap would mark a start date, second would be an end date. On tapping end, a request would be made to some simple service to calculate the minutes between them and sent to beeminder. This has some downsides; the physical element is removed and it requires you to interact with a phone to get your score. It has to work the other way. I can’t be in a state of “I can’t wait to interact with a phone to increase my score on Beeminder”.
As I mentioned in the first post, the same usb-checking script can run on your laptop - but then you have to have your laptop with even bigger screen turned on. That’s what makes Raspberry a good option.
Nonetheless, don’t feel discouraged by technical details as I’m going to share numbers (baseline + result) as well.