Yes and no.
Unlike older versions that used different compilers, 1.21.1 relies on TeaVM to transpile Java into JavaScript/WebAssembly. eaglercraft 1.21 1
If you want, I can:
experience has become the "Holy Grail" for players looking to access modern Minecraft features like Trial Chambers and the Breeze mob on school Chromebooks. The Technical "Impossible" Yes and no
The Eaglercraft community is active, but development has shifted toward over chasing the latest version. Several dev teams are working on a "modern rendering engine" that could support up to 1.20, but 1.21.1 is likely 12–18 months away , if it ever arrives. if it ever arrives.