@Divyansh Singh I would recommend to use custom connection and store the secret of your bing endpoint. I have tried adding the key or secret using these steps.
Add your bing key or secret in the last key pair and mark it as a secret.
Before creating the connection select the appropriate Access type. Use Shared instead of Project if the project owner is different.
Once connection is added, add a Python tool in your flow and update the code section to below:
Hit the Validate and Parse input button and then select the inputs of your python tool.
I used the name finaltesting.
Select it and run the tool or flow.
Here, I printed the key to check if it is correct and it should be available in your logs.
Similarly, you can use the key to call the bing search endpoint. The bing search endpoint is global and you can probably add other key/pair with the endpoint value and set other parameters in your code before a POST request is called to search.
With respect to other tools, I think more will be added soon along with guidance as this is still a preview service, use this page to check for any new tools are added in the future. Thanks!!