For your objective the best Puppy may not actually be a Puppy.
This Forum supports several species of operating systems. By definition a 'Puppy' is created using an application named 'Woof'. Woof makes use of binaries published by major distros such as debian, Ubuntu, and Slackware; however substituting 'infra-structure' unique to Puppy for the more RAM demanding, CPU-demanding 'infra-structure' employed by those major distros. Almost all Puppys use the light-weight JWM as Window manager --don't panic, a Puppy development known as JWMDesk makes customization at least as effortless as that offered by Linux Mint-- and the light-weight Rox as file-manager. A few Puppys use the XFCE-Thunar combination; and for those which don't there are choices of alternate Window & File-managers. Puppys are designed so that they can be run entirely in RAM --very fast if you have enough RAM; but can be configured to do otherwise.
All Puppys are designed to be portable, requiring only their own folder on almost any media. They also are designed to run 'as root' --no password needed to do anything; but applications can be run as the limited User "Spot". It is recommended that your choice of Puppy first be 'burnt' to a USB-Key so as to be certain it will run on your --and the other people working on your python project's computers. Almost all Linux applications designed to burn an OS to USB-Key will fail to properly deploy Puppy because it is designed as a portable. The easiest to use if Unetbootin and even the config file it writes has to be manually edited. Ask how and for alternatives. [Starting with Windows is easier].
Almost any Puppy can be used to program. As a general rule, you would have to download a file named devx.sfs --published for your specific Puppy, e.g. devx_fossapup64_9.5.sfs-- and SFS-Load it. Most people neither compile nor program. Everything 'builtin' requires some RAM. So it's not included by default. I don't do either. IIRC, devx provides the tools needed for compiling and programming in C(++?). May not be needed for python.
As you've discovered, the Forum has a Programming Section. It also has Projects Section and specific Sections for each Puppy and various categories of applications. You can use it like an index. https://rockedge.org/psearch/ is a google-search engine for 'all things puppy' that can also be useful. And never hesitate to ask for advice.
Almost all Puppys have geany. All Puppys can access the repositories of their binary-compatible 'major distro' to install other text editors and other applications. However, because much of a binary-compatible's infra-structure has not been included sometimes to obtain functionality requires a search for missing dependencies. Naturally, Puppy has a tool for that -ListDD-- you can install if not already present.
The reason Puppy may not be best for your Project is that it is not 'Mainstream'. You wouldn't set out to design a brake system for a Honda Civic using a Ford Mustang as your test vehicle.
The closest Puppy to 'mainstream' is VanillaDpup. See https://www.forum.puppylinux.com/viewforum.php?f=183 and in particular https://www.forum.puppylinux.com/viewtopic.php?t=5044. It is binary-compatible with debian, and unlike most Puppys, it includes apt and synaptic. VanillaDpup 10 is currently the version recommended by dimkr, its creator. I may be wrong, but AFAICT, there is no devx file. Best to ask dimkr on that Section what to do.
BookwormPup, https://www.forum.puppylinux.com/viewtopic.php?t=8690 is also binary-compatible with debian and has apt and synaptic built in. Although slightly more like traditional Puppys, it may be a good choice.
By the way, to understand How Puppy Works, read https://www.forum.puppylinux.com/viewtopic.php?t=5818, and https://www.forum.puppylinux.com/viewtopic.php?t=6526.
But as I wrote, the best Puppy for your project may not be a Puppy, at all. On the Forum you'll find a Section devoted to 'Debian and Ubuntu' dogs, https://www.forum.puppylinux.com/viewforum.php?f=22. As I understand it, the creation of these begin with a 'net-install' of their binary-compatible which are fleshed out before publication to be a very small Live CD shaped to look and act like Puppy Linux. Apt is built in; as is access to its binary-compatible's repositories. Again, these are designed as portables, can be located anywhere including just a folder on the partition used by some other OS.
But perhaps you best choice may be one of the Kennel-Linuxes, https://www.forum.puppylinux.com/viewforum.php?f=192. These are in fact the same operating systems --offering all the features of the specific Major Distro used except that they employ modified initrds so that those distros function as portables. There are several to choose from. Airdale --based on Void-- may be the most matured. But there are also versions including ones based on Arch-linux, Ubuntu-Jammy. If you are also running the actual binary compatible, I think there's a method by which your work under the portable can be transferred to the 'Full Install' binary compatible.