Throwing out a couple more benefits: bun is faster than node, dramatically so in some specific cases (websockets). Bun also has been doing a great job at building out core libs that probably don't make sense for node, such as the native inbuilt sqlite module, thereby reducing your dependency graph.
People shit on the node/npm ecosystem relentlessly for the typical inauditable deep dependency graph, and bun makes substantial improvements to that situation.
Edit: bun recently added an inbuilt api for manipulating images (resize, change formats, etc). Another good example of them adding native/faster functionality that replaces significant dependencies (in this case, likely sharp: https://www.npmjs.com/package/sharp?activeTab=versions)