So, I needed to use the 1password CLI from vscode-fhs, but it didn't work because the sandbox user wasn't the same as the native one.
tc001 ~/foo> op whoami
[ERROR] connecting to desktop app: read: connection reset, make sure 1Password CLI is installed correctly, then open the 1Password app, select 1Password > Settings > Developer and make sure the 'Integrate with 1Password CLI' setting is turned on. If you're still having trouble connecting, restart the app.
Thankfully this was pretty easy to solve once I figured it out, but it wasn't really doccumented anywhere.