Pass is a short bash bash script (very little code). It passes the encryption to a dedicated utility GnuPG (out of which only the AES and cv25519 routines are used).
You should use smart card to store the GPG key. Every touch of the security key gives out only one password. So if you copy the HN password, other passwords such as your bank password is not at risk.
The missing part is integration with browsers, which increases the attack surface (although it’s minimal here, since only one password is at stake), but protects against phishing.
Pass probably doesn’t need an audit, since you can just read the script.
Only if you disregard that pass doesn't encrypt file names.
Gopass does encrypt file names too.
Also, I don't know if other people do this, but I don't actually use the pass scripts, and instead have my own scripts for managing things that just happens to be very similar to pass. I extend it in whatever ways I want to.
If I cared about this issue I would probably consider putting the passwords in a file system on a loopback mounted luks volume backed by a regular file, or maybe just store them in a different format altogether.
I do realize that the average user doesn't want to bother with all of this and wants something that "just works".
The learning curve to understand all the moving pieces and the initial setup can be more hassle than many are willing to put up with, but after the initial legwork is done, adding new devices is not that much more complicated than what it is on paid services, and using it is as simple as any of the popular services, IMHO.