Why can't I construct `WebAssembly.Memory` in browsers?
This sounds like a limit that's set in your OS. On 64-bit systems, the browsers reserve 6GB of virtual memory per wasm memory object (in order to avoid bounds checks in the machine code). If your max memory is limited you may run into problems with that. The output from ulimit shows that you're limited to 8GB of virtual address space per process, which probably explains this.
Perhaps try running ulimit -v unlimited to see if this improves the situation?