I have found that the way to go on this issue, was to install it to an internal hard disk and update it on from there - 521 updates, and it took less than an hour.
It is presently running nicely, with apparently only minor issues.
The question is, can this present installation be installed back to a flash drive?
I am not an expert, but I have found the dd tool to be very useful in these situations, though if you have more than one OS on the hard drive it could complicate it.
No guarantees, but you have nothing to lose by trying it!
I’m not sure why you would want to squash the files? Is the flash drive not large enough?
I have several distros on different flash drives (most of them 64Gb), and have no issues running them directly of a flash drive without any squashed files. NomadBSD is one of the distros, and it runs very well.
That is the only way that I have seen it done, even through dd, with a fully configured installed system.
My experience has been through Linux - maybe BSD is different.
I am not confident enough with dd, that my multi-booted main drive and the m.2 installed drives might get erased permanently, with my level of knowledge (lack of).
If there is an application, or command line within Nomad, like the “NomadBSD Installer”, that reverses it, back to a flash drive, it would be a nice option.
NomadBSD Installer just does it on any volume or removable support engaging the full disk space. So you can use the NomadBSD Installer targeting an USB volume