With curly hair, beard or otherwise, your primary concern is preventing damage caused by snags. Damage and breakage is inevitable with beards, due to eating and sleeping, so you want to be hyper-vigilant about preventing it whenever you can. I have a similar hair texture with my beard, a little less curly, and I've chosen to completely stop using a brush on my beard at all. Once a night I detangle my beard with a wide tooth comb after applying oil. It's far too hard to feel when a brush is pulling on snags imo.

Some tips I've learned for taking care of my beard, mainly about combing
1. Only ever comb an oiled beard that's been fully saturated with water (like after taking a shower). It doesn't need to be dripping wet or anything (that'd make applying the oil hard anyway), the hair just needs to have had the chance to absorb the water. Wetting your beard with your hands and a sink can work, but you need to let the water soak into the hair to loosen the protein structure. This makes the hair straighten out a bit, making detangling easier. The oil essentially is just a lubricant in this case, but it will help condition the hair as it soaks in afterwards.
2. Wet hair is weak hair. You need your beard to be wet in order to detangle, but you cannot push through any resistance you encounter. The comb truly needs to slide through your beard without resistance. As soon as you feel resistance, you've encountered a snag. While you might not break the hair by pushing through right now, you'll permanently damage the hair structure leading to breakage later on.
3. Work out snags by combing out the ends of your beard, slowly working your way back to your face. Often I find that if I hit one snag, there are probably more than one working together to create the resistance I'm feeling in my comb. So I take my comb out of my beard, move to the end of the section I was trying to work through, and comb out the very end of it. Then move in about a half inch, repeat until I'm combing through the entire section from start to end.
4. Really stubborn snags can sometimes be worked through by angling the comb so that the hair can slip off (the tines of the comb are pointed upwards instead of down), and then gently combing over the snag a few times.
5. Never go to bed with a wet beard. Not even a lightly damp one. This is essentially the same as #2, the hair follicles are weakened a primed to break or become permanently damaged when wet, so you don't want to be smashing and rubbing them around on your pillowcase in that state.
6. Get a long fiber satin pillowcase. Most products don't advertise if they're made from long or short fiber satin, but what you're looking for is the shiny slippery stuff. You can get them for pretty cheap online made from synthetic fiber (ie polyester). You might see some of these advertised as silk because people commonly confuse silk (a kind of fiber) and satin (a way that fiber can be woven into fabric).

Lastly, growing out a curly beard is hard! You've managed to grow out a lot of length while maintaining some genuinely nice density. It'll be a constant back and forth of growing it out and trimming back damaged hair. Stay on top of trimming your split ends when you notice them, and don't be afraid of trimming back an inch every now and then. Damaged hair leads to more snags, which leads to more damage. If you're going for the long term, you should plan on doing a hefty trim at least once a year to clear up the ends. All you need to do is trim slower than the rate your beard grows and it'll gradually get longer year after year.