Offline developer licensing for an air-gapped dev environment, Devolutions-account sign-in not possible

Hi,
The developer licensing model changed over the last few versions and it now breaks our setup. Previously, purchasing a license also let us create offline developer licenses. Now the Developer Edition requires signing in with a Devolutions account, which needs internet access, and an offline dev license no longer seems to be available.
Our situation:

• Our development server has no internet access. It's isolated because it holds sensitive data.
• Company policy doesn't allow developing locally on workstations, so we can't develop off that server.
• We connect from the workstation to the dev server via VS Code Remote Tunnels, start the Universal instance there, and forward the port with dev tunnels. Signing in with a Devolutions account in this setup isn't possible.
• We already hold normal licenses for our production and test systems. It's only the local/isolated development case that used to work and now doesn't.
• The PSU instance on the dev server is started only during development, stopped afterwards, and used by a single developer.

As far as we can tell, the Developer Edition can't work here, and there's no offline dev license anymore, so this path is closed for us.
What we'd like to know:

• What do you recommend for teams working in an isolated/offline setup like this?
• Is there a supported way to keep developing without internet access on the dev machine?

We've been working this way for a while and are now blocked, so a clear recommendation on the intended path would be much appreciated.

Thanks, Wolf