Hi IndianKid,
On an AR, there are examples for configuring QinQ sub-interfaces to access a VLL network.
Please refer to: https://support.huawei.com/hedex/hdx.do?docid=EDOC1100007335&id=dc_cfg_qinq_0102&lang=en
S switches can access VLLs through single-tagged VLAN mapping sub-interfaces and double-tagged VLAN mapping sub-interfaces.
You can refer to https://support.huawei.com/hedex/hdx.do?docid=EDOC1100126530&id=EN-US_TASK_0177102868&lang=en
I hope it helps!