There are hoods (recirculating type w/o the exhaust hose) and vented (need the hose to vent out the air).

I think his concern (besides hard to conceal) is that it is not easy to be able to support the hose/pipe as the fittings are not that common in MY..you can find end caps easily.. but fittings to hold up a flexi duct is a good question on availability.
if you run long distance horizontally a 6" PVC pipe easier to support than a drooping flexi duct. Can either use that steel belt that look like a flattened bicycle chain, or rest it on cheap aircon bracket/any L/C brackets.

the hose will be exposed, not nice only. or do a box up plaster ceiling to conceal the hose

Ya the hood is normal install to wall I think.. based on http://www.fotile.com.my/products/user_man...017_EMS9018.pdf last 2 pages
it will mount to the wall by the metal plate
like aircon IDU drill few wall plug holes mount the plate, drop in the hood on the wall plate

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the flexi exhaust hose not conceal je. but to mount this 6" a bit tricky
to mount the hose u can either use
steel belt https://shopee.com.my/3-4-inch-Steel-Band-w...7183.4812325430
PVC U clip https://shopee.com.my/PVC-Pipe-U-Clip-Grey-...8097.6657802044
stainless steel U clip https://shopee.com.my/SIMJU-Stainless-Steel...6369.7463239986
if support pipe aircon bracket also boleh https://shopee.com.my/Air-conditioner-Brack...5057.6946224672

U clip u need to find the one that can fit 150mm if using 6" pipe or hose, above example only
6" size usually hard to find the U clip fitting as mentioned above
6" PVC pipe (mount short flexi pipe to it from the hood) then flexihose to PVC pipe (use suitable pipe clamp) maybe easier for horizontal run coz just pakai 2 aircon bracket mount the pipe horizontally vent out. Flexihose need many supports if you wanna do horizontally as compared to pipe. Pipe u bring the flexihose along with the hose clamps to hardware store to buy easier.. so confirm fit.. maybe if need to adjust 5" pipe due to ID/OD issue also can do on the spot.

But the rough idea is there lah.

Anyone with a spirit level + rotary hammer (for concrete/RC wall) or hammer drill (if brickwall) can do.. not rocket science