Ask HN: Ideas for being productive for a few months

I've been living in SF for a couple of years now. I was all set to change employers, only to get denied at the border when I tried to re-enter the US. My immigration lawyers are telling me it could take a few months to clear this up.

So, aside from all the stress and hassle trying to deal with having a whole life and apartment with all my stuff that I can't access now, does anyone have advice on how to spend a few months? My would-be employer isn't interested in having me work remotely in the meantime, and I'm not sure how difficult it is to find a temporary developer gig for a few months.

Some of my ideas:

* online courses. I'm very interested in getting more experience in ML/data science (I have a bachelors degree in math/CS) but I often start online courses and then lose motivation.

* start a side business. I'm not really an entrepreneur-type but it might be a good learning experience. Again I'm afraid that I might lose motivation; I'm not great at self-driving myself.

* contracting/consulting. But I don't have a lot of contacts or potential clients.

* travel. But I've already traveled a fair bit in the last couple of years.

For what it's worth, I'm Canadian. The bulk of my software experience is in developing real time, distributed systems. I feel like having a few months off could be a tremendous opportunity to grow myself and learn something new, but I also know from experience that I have difficulty with motivation and self-driving myself. Any advice would be greatly appreciated.