I managed to figure how to do a 0-day strat for this achievement in 1.31 Leviathan by using Concentrate Development, which ties the IGT record (Lambdax.x already did a 0-day strat on version 1.22) but I'm also fairly certain it's faster than the old RTA strat, so I could get a much better WR in that category :)
I did a few mistakes in my execution where I stumbled over hotkeys and stuff, so you could save at least a couple of seconds on this. It's also possible that the strat itself could be refined a bit; I experimented with multiple different variations on this strat and this was the fastest one I could find in terms of real-time, but it's possible there are faster ways to do it still.
EU4 speedrunning leaderboards: https://www.speedrun.com/eu4
EU4 speedrunning discord: https://discord.com/invite/BVXu7yw
Paradox speedrunning discord: https://discord.gg/R6cqEYtsTW
Paradox speedrunning subreddit: https://www.reddit.com/r/ParadoxSpeedruns/