Added marker clustering for Google Maps, aswell as two demos inside the /google-map showcasing how it works and how its done. Let me know if something looks amiss or if anything needs changing, I tried to test it as much as possible to make sure it works as intended. I tried adding the script src below to the other projects, but could only do WebAssembly for some reason.
Be wary that this is crucial for it to work:
<script src="https://unpkg.com/@googlemaps/markerclusterer/dist/index.min.js"></script>

Changes made:

blazor.boostrap.js

• Made it so that if a "content" of a marker contains <svg, it will add a class that fixes the misalignment that is specifically only for SVGs.
• Made changes to initialize, updateMarkers and addMarker to support clustering, making sure it happens the most optimal way possible.

blazor.bootstrap.css

• Added .bb-googlemaps-marker-fix that fixes the misalignment of SVG markers.

GoogleMap.razor.cs

• Added OnClusterClickJS (works the same way for markers, except for clusters instead)
• Added ClusterOptions to the initialize (see RefreshAsync and and OnScriptLoad)
• Added ClusterOptions
• Added OnClusterClick EventCallback

WebAssembly/wwwroot/index.html

• Added script src for marker clusterer.

+ Models/Maps/GoogleMapClusterOptions.cs

• Added GoogleMapClusterOptions with: Renderer, Algorithm, ClusteringEnabled and EnableClusterClick
• Added GoogleMapClusterAlgorithm with Type and GoogleMapClusterAlgorithmOptions (pardon if the names seem excessive)
• Added GoogleMapClusterAlgorithmOptions that contains MaxZoom (this may expand in the future)
• Added GoogleMapClusterRenderer that allows for custom rendering of a cluster (SVG, TextColor, TextFontSize, ShowMarkerCount)
• Added GoogleMapClusterClickEvent, should work the same way as a MarkerClickEvent.

+ Enums/GoogleMapAlgorithmTypes.cs

• Added supported algorithm types for clustering. Use enum combined with ToString() to select the different types.

+ RCL/Components/Pages/Maps/GoogleMap_Demo_07_Dynamic_markers_with_clustering.razor

• Added demo for simple clustering

+ RCL/Components/Pages/Maps/GoogleMap_Demo_08_Dynamic_markers_with_custom_clustering.razor

• Added demo for advanced clustering with custom icons, algorithm definitions etc.