As a proof of concept, the following changes on my install achieved desired name and icon improvements. Tested with Minecraft 21w11a under macOS Big Sur 11.2.3; see "Proof of Concept Demonstration 2021-03-23.png".
① Renamed "java" to "Minecraft Java" in "~/Library/Application Support/minecraft/runtime/jre-legacy/mac-os/jre-legacy/jre.bundle/Contents/Home/bin/". ② Added icon (resource fork data) to the "Minecraft Java" executable file. (Pasted icon via Get Info in the Finder.) ③ Updated the Java executable path used by the Minecraft launcher accordingly.
Glitchatic Glitch
As a proof of concept, the following changes on my install achieved desired name and icon improvements. Tested with Minecraft 21w11a under macOS Big Sur 11.2.3; see "Proof of Concept Demonstration 2021-03-23.png".
① Renamed "java" to "Minecraft Java" in "~/Library/Application Support/minecraft/runtime/jre-legacy/mac-os/jre-legacy/jre.bundle/Contents/Home/bin/".
② Added icon (resource fork data) to the "Minecraft Java" executable file. (Pasted icon via Get Info in the Finder.)
③ Updated the Java executable path used by the Minecraft launcher accordingly.