By default, my tests werent showing up as it shows in the @Tyler Liu answer, so I had to make some changes as defined here.
My.csproj:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net9.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
<IsPackable>false</IsPackable>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="coverlet.collector" />
<PackageReference Include="Microsoft.NET.Test.Sdk" />
<PackageReference Include="xunit" />
<PackageReference Include="xunit.runner.visualstudio" />
</ItemGroup>
<ItemGroup>
<Using Include="Xunit" />
</ItemGroup>
</Project>
As long as you have the C# Dev Kit extension installed, then the unit tests should show up in the testing pane and you should be able to click into the tests, set break points, and debug the tests