Sometimes I will use something and realize I’ve owned it forever. It’s a nice change in our throwaway reality. I think my personal record is a bicycle multi-tool I got for one of my first bikes, ~25 years ago. Still have it, still use it. When it comes to electronic devices I have a Panasonic mini Hi-Fi from ~2005. Never felt like changing it.
What’s your record?
When I was younger I just put a chunk of foam at the end of my regular mattress to make up the gap.
In the last couple of years a it’s custom made foam sheets with latex. Not cheap but possible from local foam shops or upholstery shops.
You can also find smaller traditional mattress manufacturers too but it’s not cheap but it’s still an option.