I tried offering equity and a slightly lower salary (20%-range lower), and then an option for no-equity but higher salary. He took the higher salary option, though I was hoping he would take the equity option.
I could revisit this with him...but I have a feeling it's not super important to him, money doesn't seem to be a huge motivator.
Exactly. Every startup I've worked for the owners have this weird attitude that their equity is worth something. It's not. It's worth jack shit until the company is worth something. It doesn't pay bills. It doesn't let me buy the new shoes I want. It's essentially an investment. Usually if someone is in the position to invest, they don't need to work a day-job to cover bills.
Just because you have weekly sprints doesn't mean the developer can't show their work more often (you just don't have the right as the PO to interrupt a developer).
I think at PivotalLabs, they have the PO's sitting near the developers.
Also, perhaps, during your iteration planning meetings, try and break the stories into tasks that feel like they are less than a day.
Also, listen more carefully during the daily standup/meeting. If the "what I am doing" is not one of the tasks or on the current log, maybe ask why. Whatever they are doing, add it to the tasks (if that really should be done).
If the answer to "what is inhibiting you" is "nothing" but the "less than" one day tasks are not complete then there is something inhibiting the developer(s). It is your job to make sure that whatever is causing the developer to fail meeting the commitments is fixed. Could be bad estimation on everyones part, could be that tasks feel overwhelming (as other people pointed out), could be the developer(s) are just not interested.