HydekIf you search Reddit for Varmilo VB660M Wireless, you'll find a thread where someone tore his apart.
The older Bluetooth mech made by Varmilo is a copy of a Leopold model, except with Bluetooth 3.0 hacked on. It differs in several ways from the VB87M, but we can assume these are virtually identical keyboards otherwise.
It has a built in LiPo (IIRC). It's semi-easy to replace its battery (requires a splicing or soldering). However, in theory a battery that only requires a recharge every six months is going to last many years. In practice it may require replacement at some point in time.