A tool like wasm2c (or my wasm2go) shows this: there is no huge runtime to carry, just a fairly direct translation of Wasm byte code to C (or Go).
wasm2c: https://github.com/WebAssembly/wabt/blob/main/wasm2c/README....
wasm2go: https://github.com/ncruces/wasm2go
Java Applets were amazing technology IMO. Windows Java launcher ruined it (as i understand that was the main security issue).
ps. Java 8 still works :P