I went to the shopping mall to buy some glue… and came back with a pir home alarmsystem with 2 remote controls for 8 euro 
is there room for an arduino+rn2483 ??? … lets take it apart
there’s not alot of room inside, but he the thing works for the price of an empty enclosure.
interesting is that it uses the same chip BS00001 as all the other china PIR’s
If you take out the electronics there is room for your own pir loralarm … thing is not waterproof
maybe a TINY LoRa inside so you can still make use of the remotes leaving the original pcb ?