The Modbus integration is quite powerful by now and has support for multiple different entities, such as switch, climate, etc.
From my point of view something like a button is missing, though. This is supported by the KNX integration for instance, and allows to send specific commands / payloads to specific addresses by pressing a button.
It can be mimicked with a switch and some automations that will turn it off again, but the button seems to be the more native way to achieve this.
In my case, for instance, I have to write a 0 to a specific holding register in order to disable the manual mode. I would like to provide a button in the UI that will achieve this.