OFDMA is part of 802.11ax standard.
And as such it only works when both AP and station are ax (won't do any good if station is ac only).
And will only be able to do something when interference is reasonably strong (not much stronger than received useful signal ... so it doesn't overwhelm receiver's pre-amplifier AGC) and when it only interferes with part of channel used by AP/station. Tests, mentioned by @syadnom in the other topic, indicate that the second condition is likely met, but doesn't say anything about the first condition.
yes, all stations must be ax to get the best experience.
However, the strong interference isn't really correct. every RU has individual modulations, so -75 noise on 10% of the band could still mean MCS4 modulation on those RUs and MCS10 on the others. So when the AP has a full scheduler, it can send data on those RUs as well. So even in low or moderate noise on part of the band you get serious benefits.
Also note that OFDMA/RUs are scheduled by RU not timeslot (or rather data is scheduled into RUs which are the 'shelves' in the 'UPS truck' that is the tx transmission), so you can fill 10 RUs destined to client 1 and another 5 to client 2 and 7 to client 3 and so on simultaneously. Ie, instead of a small icmp ping taking up an entire transmit frame, it lives in a single RU so data for other clients can also be sent at the same time. This has a massive benefit to latency for clients and airtime utilization.
For me, I need a product that can dodge noise. I don't expect noise immunity, just dodging the noise enough to have a linear affect instead of crushing it.
Also note that link puncturing comes up a lot and is basically the opposite of what people think. It's the AP scheduling around known noise/services at the AP, so that clients don't contribute to self-induced noise and the AP doesn't make noise for the other-AP clients. Ie, if you have a 160Mhz 'ax AP and inside of that channel there's a 20Mhz 'ac AP nearby, you puncture the 160 to remove the 20 (probably 30 for OOBE...) for both AP tx and CPE tx. This is how this feature works for a WISP that can't afford to give up the existing channel of their 'N or 'AC gear, just overlap right over the top and puncture for the legacy gear. This is optional in wifi6, but it looks like other vendors (ubiquiti in particular) isn't implementing it on anything until their wifi7 product comes out. It would be great to see mikrotik implement this but I doubt it'll come in the wifi6 gear.
Just enable OFDMA and we'll have a product we can work with. Ultimately, I think we need wifi7 models for some of these features to 'just come with it' since wifi7 *REQUIRES* support for OFDMA and link puncturing, they are not optional features.