Getting enterprise customers into early TestFlight builds is generally speaking not recommended because first impressions often become lasting ones. The reality of it is that even with good product/market fit, most people are too busy to play with build after build in the early days.

Assuming you have validated the core product thesis before building the app, I would try and recruit whomever you know to be great product people into TestFlight first. Building a great mobile product is exceptionally hard and I've benefited so significantly by having so many of my TestFlight users be great mobile developers, and product owners. There is a lot of very generalizable experience around what makes a great mobile app, and having people who can quickly spot bad UX will reduce your iteration time significantly.

For mobile, it's important that the polish is there before onboarding users whose favorable impression might lead to enterprise sales. It's better to test screenshots and static designs on these important users than a really buggy app.

Lastly, I strongly encourage you to switch from TestFlight to Hockey App. We made the transition after too many headaches with TestFlight.

I spend almost all of my time obsessing about attaining mobile nirvana and also built a website in the late 90s that provided personalized nutrition plans via a website to corporate employees so happy to talk to you in a call about what you're doing.