Not junk bought mail order
Noting that the seller is not Amazon. You're dealing with the ugly side of the platform, which is essentially eBay. It's populated by cheap junk from Alibaba. A quick search of Alibaba will turn up that very unit, for a fraction of that cost.
This stuff is all junk. It's not safety-rated to handle mains power, doesn't have anti-arc PCB slotting, it's not made of the right plastics to not start a fire if it burns - watch any Big Clive teardown videos and you can watch a rogue's gallery of design shortcuts that can kill you.
What you're looking for is one rated by relevant authorities such as BSI (the famous BSI Kitemark), TUV, Intertek etc.
While the CE logo is supposed to mean that, it is actually meaningless unless there is an EU "bricks and mortar" company standing behind the mark and brand, and who was physically responsible for importing it. Amazon is merely a marketplace connecting independent sellers to buyers, and is not responsible in any way. Yes, it's stored in an Amazon warehouse and ships from there, but Amazon is merely a warehouse service etc. and the item is the far-east seller's property until it arrives at your door. An ingenious loophole, letting them sell garbage and shift all responsibility for consequences onto you.
Charging 30 quid for it is nothing short of a scam.
Not that particular Triac
Even if you had a quality unit, that one isn't the right thing.
You need one that is specifically made for 2-way switch circuits. And certainly, one that is "made to NOT use neutral". Of which many exist, because your wiring scheme is extremely common, especially in 2-way circuits.
Further, they are designed to solve the physical problem of a) fitment in an appropriate location, and b) providing a physical control so "humans who are not you" can also control the light.
What you're really looking for is a "smart switch". It installs in the location of a light switch and replaces the normal light switch. Since the "no neutral at a 2-way" problem is common, there are plenty of triac smart dimmers designed to work with 2-way circuits without a neutral. What they do to power themselves is leak power via the LED light, and either you use LEDs designed for that, or a bypass capacitor made by the dimmer supplier.
Like any smart switch, they can be had in a number of data protocols from HomeKit to Zigbee to X10. They also make wireless remotes, either handheld or "velcro to wall" or designed to fit inside a normal switch box.
