Hello Nicolas,

I can share two thoughts here -

• The AutoComplete Value renders in a textbox. The ValueTemplate can only be plain text, which is not a true template. Moreover, the user experience becomes ambiguous during typing. For the same reason, the ComboBox doesn't have this feature either. Only the DropDownList has a ValueTemplate, because its Value renders in a "readonly" <span> and allows HTML markup.
• The AutoComplete Value is a string. If the data is a collection of ID-Text pairs, then a more suitable component to use is a ComboBox with filtering. In this case, users will filter, select and see friendly text (defined by the TextField), but the component Value will be the ID (defined by the ValueField).

See

• Blazor ComboBox Filtering example
• Blazor ComboBox Filtering documentation

Regards,
Dimo
Progress Telerik