The full API diff between .NET 7 and .NET 8

For the areas I help maintain, some of the new features include...

Better support for `Int128`, `UInt128`, `IntPtr`, and `UIntPtr` throughout the codebase, particularly in `BinaryPrimitives` for endianness handling.

`IUtf8SpanFormattable` and `IUtf8SpanParsable`, allowing types to be directly parsed/formatted as UTF8

Standard APIs for `Lerp` (Linear Interpolation), `DegreesToRadians`, and `RadiansToDegrees`

Removing the `where T : struct` constraint from the `Vector` types so they can better be used in generic code paths (this doesn't expand the set of supported `T`, it just means you can use the type if the `IsSupported` check returns `true`)

Support for SIMD on Wasm.

Support for AVX-512 on x86/x64

New throw helpers on `ArgumentOutOfRangeException` (`ThrowIfZero`, `ThrowIfNegative`, `ThrowIfEqual`, `ThrowIfGreaterThan`, etc)

New APIs on `Span`/`ReadOnlySpan` for searching/finding data (`ContainsAny`, `ContainsAnyExcept`, `CointainsAnyInRange`, `Count`, `IndexOfAny`, `IndexOfAnyExcept`, `LastIndexOf`, `Split`, etc)

New APIs on `Random` in the form of `GetItems` and `Shuffle`

and so much more in areas maintained by others on the team as well (collections, json, WinForms, ASP.NET, etc)