Mattresses & pillows for optimal sleep for as many people as possible

We have been working remotely for the last month and a half.

During this time I have noticed that mattresses across Portugal appear to all be hard as rock and that a thin memory foam mattress topper makes a _huge_ difference to my sleep quality. But the conversations I have had with people show that there are different preferences - some because they've never tried anything else and some because firm mattresses are their 'thing'.

So if we were to try to furnish a dwyl summer hq with beds, mattresses and pillows to promote optimal sleep for the most people (with the knowledge that one size does not fit all), what kinds would these be?