How do you convert a Xamarin.Forms custom renderer to a MAUI handler?

Identify what the renderer customized, then move that logic to a handler mapper (AppendToMapping/ModifyMapping) or a custom handler if you added a new control. Most simple renderer tweaks become a few lines in a mapper, removing the renderer class and its ExportRenderer attribute entirely.

// Old: custom EntryRenderer removing the underline
// New: EntryHandler mapper
EntryHandler.Mapper.AppendToMapping("NoLine", (h, v) => { /* native tweak */ });