thx @BurningTreeC, worked like a charm!
when I opened ./nw in terminal, I did get the message "[11774:11774:0607/091416.715812:ERROR:browser_main_loop.cc(299)] GLib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed" - but it did run TiddlyDesktop anyway, so I guess all good...
I still can't open "nw" via file mngr though - and when I right-click on the TiddlyDesktop icon in my favorites to "Show Details", I get the message "no application found". just out of curiosity, any idea why this is?
btw, adding it as a dependency in the TiddlyDesktop Readme sounds like a great idea - would have saved me some hair-pulling. ;-)