Maintain and expand existing C#/Azure application, max 200 hours per year

I am looking for someone with C# and Azure knowledge who is willing to take over an existing application from another freelancer and further develop it.
We also link the application to an ERP system through SOAP requests and to a machine with its own communication language (CSV based). The last 2 are not rocket science in themselves.

More info:
Today we are working with a programmer who actually has too little time to further develop our application due to other priorities (lasers and their firmware, he is truly world class in the industry).
Development of our app started at the end of 2018.
I can read code, but writing it myself is not my dada, which is why I have completely outsourced this.

Until now, we always worked together on a topic list via Trello, where I documented what I wanted and what it should look like in both the UI and the underlying logic or communication.
I am now more than familiar with ERP and machine communication :)

The application existed as standalone software with a local SQL database, but since 2023 it has been transformed into an Azure application with 2 locally installed apps.
An API has already been designed to communicate with, for example, a web interface or other things, although only the foundation has been laid there.
Going cloud-based has proven to be a huge advantage in terms of scalability, but also bug fixing. As a result, the applications on the client side are hardly updated (must already be a UI thing) and a small intervention on the cloud side can still provide extra or improved functionality without users being "inconvenienced".

The software for the two applications together consists of approximately 32,000 lines of code and should be able to be expanded incrementally on an annual basis.
The bulk work is over, we need 20 to 150 hours per year, although that mainly depends on the space you can make available for it and how many features are added or need to be changed. Can be arranged quite flexibly and we can certainly wait a few weeks in most cases. Sometimes we move quickly with bug fixing bugs that were not always visible at first glance.
Ad-hoc support in the event of problems is crucial, as we expect a response time of less than 24 hours, preferably less than 4 hours. For most machine owners who use the software, this is really their work tool that can potentially paralyze a production environment. So uptime is very important.
The past teaches us that this all runs quite stable and almost no ad-hoc intervention is needed, but you probably know how that goes with releasing updates or simply Murphy's law :)

I would like to hear from you if you would like to know more about this!