My whole programming career has been around custom and standard ERP and internal business apps. I am in mfg too, just not a large enterprise. Low bureacracy, easy to get things done, joy when you see your software improves your coworkers work daily. I also had an an idea of making a new ERP, something that will have a strong both financials and manufacturing and not much else, so a bit narrow focus, but it would cut a lot of baggage that first and second tier ERP carry. Closest I can think of it is Dynamics GP as a modern web app. I never worked with GP, only looked thir user guides and youtube videos, but without actual app as a reference it is hard to make any progress.

>I work for a large enterprise that has basically written its own ERP from scratch. There's a lot of rough edges but it's very tailored for our workflow and processes.

That is exactly the problem. Most ERP, SAP, Dynamics or Odoo have a fixed workflow pattern. And I argue this is no good for SME. SME dont want to adopt to the 5000 small procedures in a large enterprise, but they still want Software to enable much better efficiency. One of the SME had a very decent ERP work done with Visual FoxPro, and apart from the lack of software update and Internet connection it was doing great.

And for other small business, AirTable and Coda goes a long way.

I still think there could be a lot of work in this space. In terms of CRM, HR, Payroll, Accounting are easy, once you move into Stock, Sales, Invoicing, things become trillion times more complicated.

Edit: One of the difficult thing with off shelf ERP design for SME is that it is highly unlikely a single person in a company that has a deep understanding and overview of every single department and how everything interlinks and play. ( For Enterprise that is 1000+ employees everything is likely broken down into very clear manner. ) It very often these people telling how ERP should adopt to their workflow often end up not fully explaining the implication. And I have yet to see a single, decent off shelf ERP implemented that works.

( Working in the boss views does not mean working in the employees views, very often there is little to no efficiency gained. )

After building few internal data heavy apps with Retool I too wondered about this exact idea. My biggest curiosity is how do you break down an ERP which at the core is mostly a way to input, validate and sometimes create data. A lot of work could be automated nowadays with automated python jobs. So starting an ERP with the idea that processes should improve overtime and % of automation should go up.