- Use a volume to attach and mount to the rescue image so I have enough space to download and extract the NetBSD USB image (this still works well)
- Use a volume attached to the rescue image, but not mounted, to
ddthe NetBSD installer image onto and then boot from this volume (this sadly doesn’t work)
Linode do support booting from volumes, but it wouldn’t boot for me. I tried using
pv, but it made no difference. Maybe it’s just an issue with Direct Disk kernels?
Anyway, since I didn’t have time for experimenting and investigating any further I went for
sysupgrade instead which fortunately worked a treat and meant I finally got to NetBSD 9.3.
Just as I published this post I found this in the Linode Community.
[EDIT: 2022-11-11] I forgot to mention that the whole reason this took me so long is because of this: I have to use the “family” computer, which is basically my daughter’s, so that means when she’s at school, but then, of course, most of that time I’m working. Sigh.