I'm planning to open a small gym and am looking for management software. I don't want cloud services or a subscription fee. I use Linux in my personal life and would prefer to keep running that at the business. Does anyone have experience with this type of thing?
I plan to self host all my services and data if possible such as camera systems and maybe even the website (I found a great local website company I'll be talking with soon).
https://www.turnkeylinux.org/ check them out for a lot of your business, self-hosted needs. Odoo, like others have said, is on there. I once used moodle for new employee onboarding and training.
It was suggested to peruse a big list of projects that might work for you. They pre package a huge amount of open source projects to run on say AWS in their own linux distro. If you find a project that looks interesting you can go to that projects website and look at docs and stuff. Then run that project how you want.