Shelly 1L - UK/Irish 2-way wiring

I have a Shelly 1L that I’d like to wire to a single light that has 2-way switching.

I’ve been scouring threads on this for a few days now, to some success; I’ve had some configurations where switching via the Shelly works, but switching one of the physical lights either does nothing, or seems to cut power to the Shelly (I notice it go offline for a second). I could explain some of these various configurations that I’ve tried, but that will probably confuse matters.

I have a neutral, so no worries there thankfully.

Wiring behind the switch (after putting back to how it was for the sake of taking a picture).

I’ve got some jumper wires ready to go, but would really appreciate some guidance of what goes where, what I need to bridge/jump between. Thanks!

I see so many threads here linking to these diagrams, but I don’t think they’re as helpful for beginners as you think. I’m sure they make complete sense to electricians. They raise more questions to me than they answer (and I mean no offence here, I’m just offering a perspective):

1) the switches are German - is the up arrow thing Common, or something else?

2) the grey/black wires connected to SW1 and SW2 seem to indicate either I need two Shelly’s, or that I’m missing some wires behind my switch

I do appreciate the time you’ve taken to reply.

Fair enough, I’ll look for help elsewhere.