I would love to see XiangQi on Lichess or a suggestion for a good one. I suck at Chinese chess, but after learning it I was demolishing my friends from the headspace it gave me, the complexity really seemed to help me be a better chess player. I feel like I was an amateur "take as many pieces as you can and overwhelm the king" before and Chinese Chess turned me into a "sacrifice your pieces to position yourself better, value the pieces differently at different points of the game, and kill the king ASAP with pressure" player.
In Chinese Chess, I try playing against others and I know I probably lost in the first 5 moves often, I really suck at it, and in 10 moves I usually can tell I lost, I have never won once against a player online.
You're in luck! https://www.pychess.org/ is exactly what you want; it took the Lichess source code but adapted it to a bunch of chess variants, including Xiang'qi.
I don't have the source, but I remember read the lichess didn't want to implement other board games in their interface.
For XiangQi, I know that you can play it on playok.com (I know the rules and played a few games last time just to get the feeling, but I am more into chess and shogi...).
I played three games and lost them all. It's as you said, I felt that in the opening they knew something I didn't and they entered quickly in my camp. The strange thing is that when I played last year, I didn't have that feeling at all, the games felt pretty even - I won one game because my opponent resigned after I declined his draw offer.
If you want we can play some games some day. My email is in my profile if you're interested.
In Chinese Chess, I try playing against others and I know I probably lost in the first 5 moves often, I really suck at it, and in 10 moves I usually can tell I lost, I have never won once against a player online.