Yes, the impulse response of the speaker system is measured, this impulse is processed into a "correction impulse", then music is convolved with the correction impulse to get flat speaker response. While the measured impulse response has a long tail (say to 1.5 seconds), the correction impulse looks to be < 30 msec. And indeed, a quick listening test indicates that far fewer taps (eg, 4096) sounds fine. I also see that commercial products like OpenDRC use fewer taps (eg, 6144 taps).
BruteFIR can partition for reduced latency. This plus fewer taps makes real-time use acceptable.
Summary: yes, I think a teensy 4 with s/pdif in and out could provide digital room correction, comparing well with OpenDRC.