Yes, there are a couple of ways to use Cloud TPUs at lower priority and lower cost. If you are a hobbyist, I highly recommend trying out Cloud TPUs for free via the TPU Research Cloud:
https://sites.research.google/trc/
If you are flexible, you (or your scripts) can access a lot of compute power at odd hours!
I started the TRC program alongside the Cloud TPU program to make interesting amounts of ML compute available to a broad group of creative people, not only to academic researchers.
The TRC program welcomes hobbyists, artists, students, independent learners, technical writers, and a variety of others. We love it when the TPU Research Cloud enables people to do something that wouldn't have been possible otherwise.
I definitely recommend applying to the TRC program - please feel free to say directly that you are a hobbyist. The sign-up form is short, and it's likely that you can access a lot of compute if you are flexible and persistent.
If you are flexible, you (or your scripts) can access a lot of compute power at odd hours!