It’s just not possible to have a good generic app to serve all of them. There’s just too much variety in workflows and edge cases to capture them all, and few companies will change the way they work to accommodate the opinionated workflow of some productivity vendor.
The best solution is still to build custom applications for each company, molded around the way they work, and owned by them 100%, so they can feel fully confident that the product will not disappear or change in ways they don’t like.