As well as the main series of Citadel, multiple spin-offs have been announced: ones based in Italy, India, Spain and Mexico.
Citadel seems to lay the groundwork for one of those, the Spanish spin-off. That's because lots of the action of the show takes place in Valencia, where Sinh lived both after giving birth, and once Citadel fell. It's also shown that her father was a spy too, which potentially introduces us to characters in this spin-off.
We're also introduced to some characters and villains in Morocco, which is very close to Spain geographically, and these characters could also show up in a Spanish spin-off.
A teaser at the end of Citadel episode 6 also tees up Citadel: Diana, the first of the spin-offs, and this is the Italian version. Starring Matilda De Angelis, this was shot and filmed around Italy and Switzerland.
Beyond the teaser, Citadel's final episode doesn't tee up Diana in any noticeable way, however the events of the season could play a bearing on it, and we might see familiar characters show up. Maybe we'll find out where Orlick ended up!