Good luck.
Many layers of the financial system for small and medium businesses are used to working with QB. It's a means of communication. You can hire people who know it. It integrates with every bank and every, well, everything you might need. You accountant --internal or external-- knows it and has a process to work with it. Etc.
While FOSS is great, it isn't always better. I think FOSS works well when you have a deeply committed, enthusiastic and dedicated community around a pain point or a need. There are great examples of this, GIMP, KiCAD, Krita and various 3D printer tools being examples of this.
Accounting software? I'll believe it when, one day, I walk into my CPA's office and he enthusiastically tells me how he is asking the firm's hundreds of customers to switch to a FOSS solution.
In case it was missed, that was sarcasm. I cannot possibly imagine an accounting firm with hundreds of clients both engaging in turning their entire practice upside-down and having their clients endure untold pain just to save a few hundred bucks on software that just happens to work just fine today and has for decades.