I played Moldavia for the first time. Allied Muscovy to prevent an early invasion, also Poland guarantees your independence at the beginning. In my run even though they were guaranteeing me they were hostile so I couldn't ally them. Ally Hungary and Austria also Mamluks if you can. They are unlikely to turn hostile until Ottoman threat is gone. Start first war against Ottomans as fast as you can. In my game Austria became powerful and seized Burgundy, Bohemia, some parts of HRE, and Hungary so it delayed achievement a little bit.
You can also become march of Poland at the beginning, seek help for independece from Poland's enemies and take a portion of Polish and Ruthenian land during your independence war but I didn't prefer that way.
Also sieging down Ottoman capital lets you kill the Ottoman sultan who has pretty good stats so don't forget to do that.
For the achievement, Moldavia is definitely easier than Wallachia. Wallachia doesn't have anyone guaranteeing its independence, its neighbours are strong and Moldavia would become march of Poland and it's a landlocked state.
![](https://s2.save4k.ru/pic/G_s5bEJzds4/maxresdefault.jpg)