if you get a mangrove make sure you gain it's trust over time IMO it will take a year before he truly calms down
I've read that you can be given the illusion of "taming" when taking an animal and letting it tire out and then being calm, this is usually not hiom being calm but the build up of lactive acid in the muscles which causes cramps
so I would try taming him by just taking baby steps, start with daily maintanence and rub your had on the dirt and such and do notm force him to do anything, you want him to get used to you being there and your smell
then if he starts coming out while doing your spot cleaning then just continue, then if he approches him maybe touch him and jjust keep going farther and farther
I know a guy who did this with his nile and the thing is truly tame
it's like a tegu in some ways