It 's simple to compile python3.9 on debian:
sudo apt install build-essential zlib1g-dev libncurses5-dev libgdbm-dev libnss3-dev libssl-dev libsqlite3-dev libreadline-dev libffi-dev curl libbz2-dev
wget https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tgz
tar -xf Python-3.9.1.tgz
cd Python-3.9.1
./configure --enable-optimizations
#nproc value is 4 in my pc platform
make -j 4
sudo make altinstall
How to compile python3.9 and install it on openwrt?
root@OpenWrt:~# cat /etc/banner
_______ ________ __
| |.-----.-----.-----.| | | |.----.| |_
| - || _ | -__| || | | || _|| _|
|_______|| __|_____|__|__||________||__| |____|
|__| W I R E L E S S F R E E D O M
-----------------------------------------------------
OpenWrt 19.07.7, r11306-c4a6851c72
-----------------------------------------------------
root@OpenWrt:~# uname -a
Linux OpenWrt 4.14.221 #0 SMP Mon Feb 15 15:22:37 2021 x86_64 GNU/Linux