OK, back to the very first post…
There is a way to do this with a fibaro dimmer 2 because the first input is intended to control the current and the second input only sends central scene information to the hub. Which means if you use the second input, you are not turning the current on and off. The switch talks to the hub, the hub talks to the bulbs. So far, so good. If there’s a minimum load requirement that you are not meeting on the first input, you can add a bypass there.
Using Fibaro Dimmer 2 with a Switch but No Load?
However, @anon36505037 has previously said in the U.K. that you can only use this on a secondary switch in the room because safety code requires a manually operational switch. Which you would not have if this were the only switch in the room.
This can work well if you have a two-way set up and you just want to replace the auxiliary switch. But most UK bathrooms are only going to have one switch in them for each light.
So… Technically, yes, it can be done. Legally, I just don’t know.
There is an alternative that some people which is to leave the original Pull switch in place Just as a manual back up and put a battery operated device on the wall that can do whatever you want to. Several people have brought that up in this thread already, so I assume if you want any more information about that you’ll ask.
I’m tired today, but I’ll try and dig up the previous threads where we discussed the fibaro 2 option. The first time it was in the context of a large kitchen which had a two-way set up, so it made sense to use it for the second auxiliary switch and then take advantage of the central scene options.
But then it came up again in the context of another room, and that’s when Robin brought up the code issue.