Some of the changes:

• System.Text.Json now provides the JsonSchemaExporter type, which supports generating a JSON schema that represents a .NET type.
• System.Text.Json: The JsonObject type now exposes ordered-dictionary-like APIs that enables explicit property order manipulation
• [GeneratedRegex] on properties
• The Regex class provides a Split method, similar in concept to the String.Split method. With String.Split, you supply one or more char or string separators, and the implementation splits the input text on those separators.
• Generic OrderedDictionary<TKey, TValue>
• ReadOnlySet<T>
• new Base64Url class
• System.Diagnostics.Metrics now provides the Gauge instrument
• NuGetAudit now raises warnings for vulnerabilities in transitive dependencies
• dotnet nuget why
• MSBuild BuildChecks
• C#: Partial properties
• ASP.NET Core: Fingerprinting of static web assets

I exclusively use Visual Studio Code for editing code. I primarily work with Go, and a little bit with JavaScript/TypeScript, but I need to do some C# work.

I have no interest in using Microsoft's proprietary C# Dev Kit or dealing with their licensing terms. What capabilities am I losing? The marketing materials for the dev kit talk about a lot of stuff that appear to be features of the open source C# extension, so it's unclear which features are actually exclusive to the dev kit.