As a very small company, how can I publish apps in-house only?

Hello, my company consists of only about 10 employees. We want to develop apps for employees only, not publish them to the App Store. I've read that in-house-only releases require an enterprise developer account, but to qualify your enterprise needs 100+ employees.

Which program should we choose to build apps in-house only for our 10 employees? How would we release them, if not through the App Store?