You will be able to build your own extension with any backend in the future, but I'm curious what you're looking to gain from that?
I don't know whether GDB understands the Wasm-specific constructs in DWARF, while the current integration uses LLDB under the hood, which does support those.
It would be nice to have more than one debugger for a given target, mostly.
I guess you'd have to make series of patches to GDB to make it work, as well as to build your own DevTools extension once the API is stable, but in theory should be possible, yeah.