There's 3 things that really stand out for me that I would say made a massive difference to my life:
Cordless screw driver. Bought the day after building a flat pack bed with a crappy screw.driver that just shredded my hand. Thought it was frivolous at the time, but I've used it so much since. It's light, small enough to fit in my pocket and good for 90% of DIY tasks.
Tassimo coffee machine. Bought it 9 years ago, use it every day. Nice quick easy coffee. What's not to like.
My first DSLR camera. It was a Nikon D50 back in 2005/6 and it sparked my interest in photography to this day. It gave me a hobby I can take lots of places and do it alone or with others.
I never loved the D50 camera itself, but I did get some really nice shots with it
My Panasonic Lumix GX80, it is the camera that made me take a deeper interest and develop my skills in photography. I had a Canon EOS 400D as my first decent camera but due to work my interest fizzled out for a few years. Then at another job I got my GX80, and started learning for real, last spring I upgraded to a Lumix S5, and I am considering complementing my camera setup with a Sony A7 IV for it's excellent AF.
My Philips Hue system has been absofuckinglutely amazing, I live alone and being able to turn my lights on before I open my apartment door during winter after work really makes a huge impact on my mwntal health, getting to open my front door into a cozy apartment instead of a black hole is fantastic