This paper presents the design and experimental validation of an all-dielectric and transparent metagrating-based metalens. Leveraging multiple guided mode resonances simultaneously, the metagrating enables the generation of two or more spectrally narrow reflection peaks. These peaks are achieved through the precise engineering of guided mode resonances, allowing for the reflection of a comb of vibrant and saturated colours. In addition to the investigation of underlying mechanisms, we introduce an analytical numerical method that facilitates rapid engineering of the spectral positions of the reflection peak comb. Experimental validation is provided for a bichromatic sample. Such metagrating can be promising for augmented reality systems, supporting individuals with mild to moderate cognitive impairments by delivering visual and textual stimuli that can improve indoor navigation, home safety, communication, and decision-making.