Most likely the source code alone is not enough, probably the system works with third party paid cloud services or third party components that could not be licensed.
Can’t release those publicly, so you’d need someone to hold the domains, the certs, they private keys, and operate the servers. That costs money, so they’d need to collect payments and manager customers. Starting to look an awful lot like running the company again.
You probably also need the customer database including user accounts and user data. Obviously can’t release that, so you’d need some process to release everyone’s data individually on some ongoing basis.
And you couldn’t release any code that was licensed rather than owned, so users couldn’t build most software anyway without acquiring their own licenses for that 3rd-party code.
There are so many problems with this idea that would prevent it from being viable.