I could not do anything for xamarin android nuget package.
All actions are generate this message:
"Unable to get repository signature information for source //api.nuget.org/v3-index/repository-signatures/5.0.0/index.json."
Please check your nuget.org's source. You can find it via Tools => Options => NuGet Package Manager => Package Sources.
The Source should be https://api.nuget.org/v3/index.json.:
Try restarting Visual Studio, I just had this issue and a restart resolved it for me.
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