Raster layer storage allows you to connect to external S3 storage, create raster datasets directly there, and link to datasets that are already stored in the bucket. This enables you to keep large, heavy rasters in cost-effective cloud or self-hosted S3 storage, while still using them in NextGIS Web like regular rasters: applying QGIS styles, including them in web maps, and publishing them via standard protocols.
Video: https://www.youtube.com/watch?v=fp_32OD3Fwo
Article: NextGIS Web support for external S3-compatible storages | NextGIS