When conditions are good, I have worked USA SSB stations with 2.5W from indoors with just a whip!
10m (28MHz) remains one of my favourite bands. At dead of night and in the quiet solar years, it acts more like a VHF band. In the Es season it is good for DX up to 1500km often, and occasionally much further. In the better years there is worldwide DX via F layer. Antennas can be small and simple. Often QRP only is needed.
See https://www.cqww.com/ .
See also https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/10m-operation .