Device limits and routers

on the zigbee2mqtt FAQ page there is an information about 20 devices limit with CC2531 coordinator.
I currently have 5 bulbs (Xiaomi Aqara LED bulbs) acting as routers and bunch of battery powered end devices (some connecting with routers, some directly to coordinator). My plan is to buy more bulbs so the total number of routers will be 20+.

The questions is if single CC2531 coordinator stick will be able to handle 20+ routers?
Can a router (bulb) connect over other router to overcome the 20 devices limit in coordinator?
If not, what are the alternatives?

According the documentation, the coordinator has a limit to 15 end devices

Because you have routers, those can also have end-devices.

I’m still learning about this topic but this is what i know.
I wonder what the limit is of the coordinator with his memory because the coordinator should no all devices (also behind the routers… I guess)

The FAQ page mentions 20 devices in one place and 15 in other.

I know i can have end devices connected to router but my concern is if i can have 20+ routers connected to coordinator or can router be connected to other router which will be connected to coordinator?

Eventually how to handle this kind of situations with high number of router devices?

You can daisy chain as already suggested. My experience is that once you get above about 40 devices the CC2531 will struggle. I upgraded to CC26X2R1 and it’s a lot more stable since then.