In Australia we have numerous hardware outlets and online retailers selling a multitude of smart plugs based around the ESP8266 platform. These generally retail between $15 and $30 each and can be easily flashed to an alternate firmware such as Tasmota or ESPHome or even MicroPython if you're daring. It generally requires you open up the device however.
This allows you to do all sorts of incredible stuff such as not having to use some half-baked phone app to turn the device on and off, as well as set up custom timers and more easily integrate into a home automation scheme. As usual, in most cases these require you to open up the device. I take no responsibility for personal injury etc and this is all educational and will void your warranty etc etc. Some of these devices can be flashed using Tuya Convert assuming you've got a spare RPi lying around and that your device is suitably old enough to have escaped a firmware upgrade that patches the vulnerability that it exploits. In my case, none of my devices worked.
These are a (formerly) ubiquitous model of power switch sold by a brand called Brilliant. These are more difficult to find now, but for a long time they were available from Bunnings for $15 each in the lighting section but no longer appear to be stocked. Opening them up is incredibly straighforward requiring only a philips head screwdriver, with the only caveat being that you must pull out the circuit board with the TYWE2S chip on it so that IO Pin Zero can be grounded for the purpose of entering into flashing mode. The pins can also be somewhat difficult to solder to as they are quite close together and all on one side. Once you've connected it to your serial adapter, it is very straightforward with Tasmotizer or esptool to get it loaded onto. Afterwards you should be able to load in the device template and go from there.
I made the terrible decision to purchase one of these for $20 from ALDI one day. Huge mistake. Not only are they horribly bloated to the point where they take up the space of three power sockets, it also refused to flash with both Tuya Convert and esptool despite using the same TYWE2S as the Brilliant. On top of this, I managed to strip the pad from GPIO Zero meaning I couldn't flash it even if I somehow figured out how to. Do not purchase one of these bastard devices unless you're going to stick with stock firmware and it's suitably marked down. It's held together with triangular screws which are particularly deep-set meaning you'll need to engage in weird tricks of dexterity to pull it apart in the first place. As well as the aforementioned issues, some people have reported that these switches randomly activate for no particular reason, although this is suppposedly rectified in later firmware revisions.
These switches are sold online by Kogan and are reasonably similar to the Brilliant plugs except that they lack a USB port for charging things with. They also use triangular screws much like the Medion switches but unlike those, the design is such that they're easily accessible and easy to undo with one of those small torx sets (you know the ones). Like the Brilliant, you also have to pull out the circuit board to get access to the chip which is in this case a TYWE3S. In this case, all the necessary pins are on the back of the chip meaning it's much more straightforward to solder everything onto there compared to the others. After this, simply flash with Tazmotizer or esptool etc and load in the template. Be careful that you don't strip the screws when either undoing it or putting it back together and that the circuit board is back in place properly, otherwise the button will be permanently held down by the plastic cover and you'll be unable to use it. Compared to the Brilliant, these are easier to solder the TX and RX leads onto and they're slightly cheaper.
This isn't technically a plug device. Instead it's an RGBW light bulb with a TYWE3L chip in it. You'll have to pull it apart to get to the innards, and this is a fairly straightforward matter of popping the top off and then pulling the LED matrix off of the header. These devices seem to be identical to the Mirabella Genio bulbs and the pinout is the same. You might have to glue it back together though as it doesn't always hold.