It sounds like you Azure Virtual Desktop might be a good fit for your use case. AVD allows you to create and manage virtual desktops and applications in the cloud, and provides a secure and scalable way to access your applications from any device.
Once the virtual desktop is created, you can assign it to your developer and provide them with the necessary credentials to access it. Your developer can then connect to the virtual desktop using the AVD client and install the necessary tools and software for your VSTO tool development.
https://docs.microsoft.com/en-us/azure/virtual-desktop/overview
You can find more detailed instructions on how to set up a virtual desktop using AVD in the Azure documentation.
I hope this helps! Let me know if you have any other questions.
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