1. add lines below in the LXC container config file
#ppp
lxc.cgroup.devices.allow = c 108:0 rwm
#fuse
lxc.cgroup.devices.allow = c 10:229 rwm
#loop0
lxc.cgroup.devices.allow = b 7:0 rwm
#tun
lxc.cgroup.devices.allow = c 10:200 rwm

2. execute this inside container (as root)
cp -a /dev /dev.old
apt install sshfs
cp -a /dev.old/* /dev/
mknod /dev/fuse c 10 229
update-rc.d -f udev disable