How to authorize a request from Power Automate Desktop to Dataverse?

I'm looking for some advice about authorization for a request I'm making in Power Automate Desktop using the action 'Invoke Web Service'. I'm using this request to get information from Dataverse.

I've currently set up this request using OAuth2.0 with the Grant Type set to Implicit and I've hardcoded a token value into the header. I'm pretty green when it comes to authorization, so I'm just wondering if that's the best way to use OAuth2.0 to get info from Dataverse to PAD? I'm also concerned this token will expire and how to go about handling that. If I should set this up differently please let me know. And if you know how I can refresh the token automatically somehow, advice would be great.

I'm going to make the assumption that you have an Azure instance within your org.

You should be able to execute the entire OAuth flow through PAD given you can do it through Postman ...

https://learn.microsoft.com/en-us/powerapps/developer/data-platform/webapi/use-postman-web-api

... having said that, if you want an easier way, my suggestion would be to use LogicApps as it does all of the hard work for you. It will also protect keys, etc. that run the risk of being exposed if contained within a PAD flow and that's even if your store that sort of information in a KeyVault or something. At some point, it needs to be exposed to PAD.

You can create a LogicApp that's triggered by an incoming HTTP request ...

... and have your DataVerse connector pull the relevant data ...

... to then return back to the calling PAD flow with a response action.

This is an example flow ...

I haven't gone into detail given your question lacks specifics around filtering, etc. but you can always make your LogicApp more comprehensive by adding functionality in the payload to order, filter, expand, etc. on the OData call to DataVerse so you get exactly what you want from a data perspective.