not documented but consisted of some sort of random application of these commands

sudo add-apt-repository ppa:vbernat/haproxy-2.4
sudo apt install dpkg-dev
apt-get source haproxy
mv haproxy-2.4.7* dev/.
cd dev/haproxy-2.4.7/
sudo apt install devscripts
sudo apt build-dep haproxy
debuild -b -uc -us
dpkg -i haproxy_2.4.7-1ppa1~focal_amd64.deb 
haproxy -v
sudo systemctl status haproxy

mkdir LibreSSL
cd LibreSSL/
wget wget http://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-3.3.5.tar.gz
tar xvzf libressl-3.3.5.tar.gz 
cd libressl-3.3.5/
cd ..
mkdir target
cd libressl-3.3.5/
./configure --prefix=//root//dev//haproxy-2.4.7//LibreSSL//target --enable-shared=no
make
make install
cd haproxy-2.4.7/
debuild -b -uc -us
dpkg -i haproxy_2.4.7-1ppa1~focal_amd64.deb