You can sideload. I've sideloaded some things on Quest, and as far as I can tell from googling it's the same on Go (I don't own one though).
However, in practice it's not going to get any new software, because developers will be writing for new generations, and porting to hardware with a slower GPU speed is more effort than it's worth.
However, in practice it's not going to get any new software, because developers will be writing for new generations, and porting to hardware with a slower GPU speed is more effort than it's worth.