The typical way of monetizing fully Open Source Software is offering paid support contracts, though the exact method of doing such varies.
It's understood that free software is provided AS-IS. Issues can be created on the tracker, if enabled, but will be gotten to on the maintainers' time and schedule, and prioritized based on the maintainers' interest.
A simple way monetizing that relationship is to accept some form of payment to prioritize issues and support, though you do need to be careful not to let it appear as "give me money to control the project's direction."
That, plus companies actually can be quite easily talked into buying support contracts, because paying for guaranteed support makes the use of a product feel more secure. You just have to make it simple for the company to do so.
The people who use your work probably would love to support it with company funds, you just mainly have to make it easy and obvious to appeal to those who have power over the budget to give you that contract.
It's a lot easier for a company to expense a $10K support contact than to send of a $20 donation to an OSS dev.
Side note: if you're interested in OSS monetization, you should probably seek out some of the projects where that's the whole idea, such as TideLift or OpenCollective. There's one that brands itself as a "license vending machine" but I can't find the name right now.