Good stuff! I have come to many of the same conclusions and even many of the same implementations—especially Make as the primary developer interface to a project.

My variations include:

• avoidance of external virtual environment and dependency management (poetry, pipenv, etc.) because they do not yet provide enough value for their costs (given my particular value weightings)
• slightly more standard Make target names (e.g., “dist” instead of “build” (and I use “build” as “do whatever is needed to make this a working dev environment”); the ones in this video are very close and I don’t see a reason for them to change; for details see https://www.gnu.org/software/make/manual/html_node/Standard-Targets.html#Standard-Targets

Here’s a representative example of the style of Makefile I use: https://github.com/flowoilwell/otable/blob/master/Makefile

Here’s a slightly more complex example; I especially like how coverage is done in this project: https://github.com/benji-york/manuel/blob/master/Makefile