Cloud TPU VMs are generally available
Founder of the Cloud TPU program here. If you'd like to experiment with TPU VMs for free and are willing to share your work with the world somehow (e.g. via publications or open-source projects), you can apply to participate in the TPU Research Cloud (TRC) program here:
<a href="https://sites.research.google/trc/" rel="nofollow">https://sites.research.google/trc/</a>