This can be cheesed by using the "backup saves" the game makes for you and on Easy difficuly (confirmed).
There are 10 save slots. Each one will have your "backup saves". At least one of them should have occurred before the death (probably more if you quit as soon as you die). It is confirmed as long as you reload a backup save that shows 0 deaths at the stats guy in town this ach will pop.
I have tested it for you and can confirm that my save on a run at 1h35min has two deaths on the stats at the guy in town, but the one on that same slot at 1h27min in the "backup saves" shows 0 deaths at the stats guy. Two PC players below have confirmed this works. You should only loose a couple minutes of progress since the last time the game made a "backup save".
The only way to see if a death has registered is to talk to the stats guy in the village (above shard vendor).
Here is a legit 0 deaths on Normal run in under 4 hours. Overflow + Catalyst + Lifeforce + tree seed Quest's 25% dmg boost is OP. You could also get the 25% dmg boost from Midnight Burrows light puzzle tree (see my hard mode solution).
The patch to fix achievements has been released. However, it disables fast travel from the map without purchasing the ability, which *could* impact trying to combine lightless, shardless, and look at the time (speedrun). However, a TA user already did a 3h 20min run without buying the fast travel upgrade, so it is still entirely possible to do lightless/shardless/immortal/look at the time all in one run on Easy. We have confirmed that all of them WILL unlock on easy as well.