IBrowse 3.0 will be written for AOS 4.
IBrowse 2.3 is currently AOS 3 and 68k at present, once that is complete and features and bugs sorted then v 3 will be done.
Linux programs are difficult to port and they use X Windows for the GUI stuff and that has to be re-written for AmigaOS using Reaction or MUI or whatever GUI you choose. Not an easy task.