#!/bin/sh
export BLAH_API_KEY=blub
...
exec /the/thus/wrapped/program "$@"

$ doas pkg_add pstree
...
$ pstree | grep sshd
 |-+= 70995 root /usr/sbin/sshd
 | -+= 28571 root sshd: jhqdoe [priv] (sshd)
 |   -+- 14625 jhqdoe sshd: jhqdoe@ttyp6 (sshd)