You don't always need to use a dedicated hood cleaner, although there are great products out there. AutoGlym being the safest one.
If you use renovo to recolour it, be very very careful. Lots of not so good stories on the internet if all previous products, dirt and cleaner not fully removed from the hood and instructions not adhered to.
The main thing, is getting the dirt from inside the seams and grooves etc out. Spend time in areas, dont rush it. As has been mentioned, a vacuum and tape will help remove the looser debris, before a clean. A good APC (allpurpose cleaner) can be as effective as a specialist cleaner, small brushes for the seams and corners are a must. You'll know where the worst areas are. Also, if you keep to smaller area, reapply a cleaner and agitate into a foam. If the foam still changes colour, it's still dirty (make sure your brush is rinsed though and it's not just older dirt from the brush dis-colouring the foam)
Once done and dry, I also recommend Fabisil Gold to waterproof the hood. Here's a link to a thread where I posted instructions on how best, I found, to apply it. This waterproofing process will help cut down on green sticking, as the hood should stay drier. If you garage, there is less need, tbh
https://www.porscheclubgb.om/forum/FindPost/996453