Are there square/ rectangle/ U openable/ open panel conduits that have one side panel that can be opened & closed?
Surface mount gutter if you want the wireway where the red box is would work. Wire mold also makes some listed wireways that look much nicer than standard gutter. Added per op comment, if there are taps in the wireway / gutter it must be accessible per NEC 378.56, but if just used like conduit it can be concealed the same as conduit. There are 2 main types some are hinged and some have a flat metal cover that are screwed to the gutter. I am sure with some clever trim it could be easy to conceal and open at a later time, the max fill is 20% 376.22.A and the nice thing is less than 30 conductors no derate is required. 376.22.B.