Discovery's spore drive of course represents one obvious work-around to the Burn in the PrimeVerse. Ok, fine. But what if the best way to work around the Burn is to go somewhere that never burned at all? What if Kovich is so interested in the Mirror Universe and the Terrans because the PrimeVerse Federation plans to somehow cross over everyone to the Mirror Universe and take it over. Spore drive seems to have potential to be adapted for this purpose. If the Primers dump all the Mirror counterparts in the burned Verse, then the Primers would have basically a non-burned copy of their Universe that could put them on track to be normal again. It would be out there...but blowing up all the dilithium was out there too.
First thing I would do, is send out Discovery to replace the lost Subspace relays, to re-enable communication across the galaxy and to make a full assessment of what remains, which worlds can offer information or resources to others.
I'm not clear from watching as to whether subspace still works the same. Hey, you know what else might work? That dimensional shift beaming tech that the rebels used in The High Ground. Yes, it kills people after ten or twenty transports, but you could beam a computer or equipment between planets with it. Was a distance limit ever discussed? What about Iconian gateways? I find it hard to believe the Feds never cracked that tech in 800 years. Whatever temporal tech Daniels used, it seemed to plop you wherever he wants you to be. If you set the time frame to the present, I don't see why it wouldn't function as an interstellar transportation device. The Borg had a working spatial trajector in 2400. Seems like the Federation should be able to adapt that. Could the Federation find and clone Tin Man spaceship organisms?