I've just started with LuckFox ProMax and install ubuntu.
I've met same promblem. gcc fails to link any c/c++ code.
So I make quick fix for this problem:

#!/bin/sh

# run on device in user's home dir /home/pico
#
# bash luckfox-gcc-fix.sh
#

# view contents:
# https://packages.debian.org/sid ...

网上没搜到官方群，只找到了供应商建的交流群。加了一个群，但是人不是很多