I don't know if this is what you were referring to, but for everyone else: this is actually super easy to add with Wireguard because Wireguard just uses Linux networking you can do things like:

  $ tc qdisc change dev eth0 root netem loss 0.3% 25%

(Lose 0.3% packets on average, but each packet is 25% correlated with the last packet loss, to produce bursts.)

  $ tc qdisc change dev eth0 root netem delay 100ms 20ms distribution normal

(Add mu=100ms, sigma=20ms normally distributed latency.)