In chapter 188, Nichirin explains that he is able to channel his "qi" (life force) into his sword as well as his robotic legs in order to use both as extensions of his body. This would imply that Atomic, who does not react to Nichirin's show of power where he quantum tunnels through the apple and cuts up the hill behind it, used Qi to unlock the Sun blade (extension of his body) and may also use Qi for some or all of his attacks. In my mind Atomic having qi mastery would explain how he was able to kill that MA fodder monster with his toothpick.
This is one of two references to Qi in the manga. The other is "Qi Gong" in chapter 192, when King begins his training arc by going around to ask various martial artists. The Qi Gong martial artist refuses to teach King as he is "already aware of King Style Qigong arts", which I believe is likely tied to the public perception of the ULTIMATE HELLFIRE BURST WAVE MOTION CANNON. To put it short, I think this chapter implies that attack is an imaginary qi blast... makes me wonder if Blast's blasts are also Qi blasts or different.
But Qi is definitely a thing in OPM, there was also the reference to "Chi" in the webcomic version of the psychic sisters arc when Fubuki said that Saitama's chi was too great for Tatsumaki to move.
Do psychic users have something to do with Qi channeling? Not clear.
Do martial arts like WSRSF and WICF use Qi? I think that's very possible, but there's no hard proof.
Do all living things have qi? Using the ancient Chinese conceptualization of it, yes. It would be nice if the manga elaborates more on qi in one of the later arcs.