Would it make any sense to use open source browser like Mozilla and port it to Amiga?
Try a quick search of mozilla, firefox and amizilla. Considering nothing has ever come out of these projects I'd say "no". It's just too large project for the amount of active skillful developers left.
For example AmiZilla started somewhere in 2003 I believe, and now 5 years later it hasn't really progressed much. It wasn't exactly hard to
predict however.
But something
much simpler than Mozilla would be possible. It'd still be pretty darned slow, however.