Should I be installing software based on Debian instructions?
Your question is not very specific. Generally speaking: As PureOS is derived from Debian your best guess to get a software installed is following the instructions for Debian. But nevertheless you might run into problems, because not all packages in Debian are also in PureOS and some packages and/or their defaults differ.
Yes, sorry for the lack of detail. I meant to say, if given a lack of a reference to PureOS specifically, should I be using Debian related instructions for installations of packages.
I use the dpkg command for one package I get from my VPN vendor. I have not had an issue, but it is only one item and not a dev tool.
All debian developer tools are available in PureOS. Because we employ the maintainer of git-buildpackage we tend to use git-buildpackage as our main package building tool, but the entire dpkg suite along with debhelper is available. So are all the needed libraries like build-essential and devscripts, et al.
As long as you have a deb-src URL in your /etc/apt/sources.list you can also simply
apt source <foo> to get the source of a given package.