Denmark has the smiley face plug. It works fine if you don't need a grounded connection, but still.. they have a lot of sockets that don't follow the EU standard.
I think France has the one where the ground pin sticks out? That can be a problem depending on which cable you have.
And then there's UK of course, though they're not part of EU anymore.
We have the UK plugs in Ireland too and we’re in the EU. I wish it was feasible to switch to the europlug, I wouldn’t have to carry a handful of adapters around when travelling.
Your comment really got me thinking. Or actually continue thinking since I recently met some N.I. relatives in France and noticed their plethora of plug adapters. I almost forgot Ireland (the whole island) uses a UK style plug as I haven't been there in a while due to life and covid, and meanwhile have travelled a lot in Europe. Meanwhile, I grew up in Canada (US style plugs), recently lived in Japan for a decade (US style plugs), recently traveled a lot for work between Japan and Europe, but sometimes also UAE (UK style plugs). I just moved to mainland Europe and living in Ireland is a possibility someday.
In tech circles like HN, I have seen the UK style plug and its fuse and local power switch lauded for its superior safety, but it's really just belt and suspenders added to make up for old, cheap not forward-thinking design. I like US style plugs because they are small, and for portable stuff often have a folding design that saves space. But I'm biased because I have only lived in Canada and Japan until recently so naturally all my stuff uses this standard.
In addition to that I am a huge nerd about plugs, chargers and travel adapters. Anything I have that is remotely portable is usb-c powered. I've hacked every old wireless mouse, keyboard, headphones that I own to use usb-c to reduce the number of cables and adapters I need for life and travel to the minimum[1]. I don't recommend this to you or anyone else but when I do end up with a UK plug power source, I use a plastic pen lid to brute force my europlug adapter into a UK socket.
Changing to europlug in Ireland is an interesting topic. It would be so tough to phase-in europlugs given that one of the differences is the UK plug with fuse is possible to use with ring circuits. And changing existing ring circuits to radial (each circuit goes back to the breaker box on an independent wiring run) would be expensive enough in wood-framed houses/North America but incredibly expensive in Ireland. Ireland is famously mostly deforested, so old houses are usually stone and new ones are usually concrete. On top of that, Ireland didn't experience recent destruction and rebuilding/postwar-rebuilding like mainland Europe did. A lot of houses[2] are very old, and many are protected cultural assets even if privately owned so you couldn't just send any old contractor in to start drilling holes and carving out channels or adding wall-mounted conduit for new wiring. It wouldn't be popular to spend on this or to potentially scar a lot of historical or family homes.
On the other hand, post-brexit there could be enough will to align more to the single EU marketplace. I don't want to be that guy that speculates "just do this" on a topic I am not an expert in, but I didn't find any serious proposal or discussion by googling it. I think the solution would be to require local outlets or permanent adapters that assume the function of the fuse in UK plugs at each outlet, and provide both EU and UK plug compatibility. You wouldn't want to allow temporary adapters because any unqualified person could make a working but unsafe configuration. You wouldn't want to force EU plugs on everyone because that would also encourage unsafe modification/adapters, or be unpopular/expensive by requiring modification of an antique device.
[1] If you are comfortable with soldering, filing, 3d printing and taking things apart, you can find usb-c sockets with the appropriate resistors installed, and tiny dc-dc converter boards with usb-c input on aliexpress, and easily update old low-power, stuff from micro-usb, barrel connector, etc to usb-c. I even added usb-c power to my NES, SNES, gamecube, wii and wii-u.
[2] I say houses and not buildings because I want to highlight the considerations for the average person, and I also presume anything commercial or open to the public already mandates using the latest building codes and safety features above all considerations. This is evident when you visit a beautiful ancient castle or church and see a jarring green exit sign, or handrails and conduit laid all over the place on top of ancient stonework. Of course, many of these places due their best to conceal modern things and keep everything beautiful except for the green exit signs. But Ireland would have to commit to funding the work to upgrade all of the family heirloom old houses.
I think France has the one where the ground pin sticks out? That can be a problem depending on which cable you have.
And then there's UK of course, though they're not part of EU anymore.