Having received some really helpful advice from @BorrisTheCat and @johnwill1 on my sockets and switches thread I'd love to tap into the wisdom of the group again for another query.
I'd like to be able to control a cooker hood through automation whilst retaining the physical switch function on the hood control panel too.
I think it's straightforward with a relay module in the back box but only if the cooker hood has a push button switch to control the hood rather than an electric switch on the hood.
If you get a hood that supports HomeConnect - 'there's an app for that'. My Bosch dishwasher has HomeConnect and I have it sending notifications to my phone, dashboard, Sonos etc when the program is complete (God only knows why....I've no excuse now for not emptying it...own goal!). I can also fully control it using that app. That would allow you to add it into automations and rules (switch on with humidity maybe?). Some manufacturers use similar apps such as ThinQ used by LG but although there is an app for that (I use it to tell when the fridge door is left open, filter needs changing etc), the app is no longer supported.
Another method would be similar to what @snell suggests. A switch module that connects into the wiring. Unfortunately, then you'd be invalidating warranties as you'd need to intercept wiring/connections from the inbuilt buttons - it might be neither practical or possible. I'd be looking at model with WiFi so you can control it that way.