I have as my main workstation a ThinkPad X201 running OpenBSD 6.3. 4GB RAM and 120GB SSD is quite enough for my needs.
In OpenBSD I use ksh, i3wm, xterm, vim, vimwiki, mutt with offlineimap, syncthing, qutebrowser/Firefox/Chromium, ranger, feh, mpv and zathura plus an assortment of helper programs and things I’m trying out.
I try to use as many textbased programs as is useful and with vi key bindings if possible.
Necessary for me is to remap the CapsLock key to Escape and Ctrl with
setxkbmap -option 'caps:ctrl_modifier' and
xcape -e 'Caps_Lock=Escape' in .xinitrc.
I use a CAT S41 mobile phone which I sync files to with syncthing through a USB connection for viewing video and listening to music and podcasts offline.
I used to have a fanless fitPC3 LP with a flickerfree Eizo monitor and Filco Majestouch 2 Tenkeyless with Cherry MX Brown, a very nice keyboard imho, but in the end the computer felt a little too slow for me. The total power consumption for that setup was between 10 and 20W.