As for “supporting the dev” I don’t really get this concept.

It can be both.

• You love the app, you don’t want it discontinued; you pay to continue the developement.
• The developers have a solid business model without any shady practices and have such an awesome free version that you don’t feel the need to pay to upgrade to premium features; then you may pay just to just your gratitude. Niagara Launcher & MixPlorer are similar examples of ad-free FREE versions.

As for “supporting the dev” I don’t really get this concept. Do you know them personally? Surely the point would be to support development of something you want rather than the people behind it. I’m in favor of supporting software development if it doesn’t violate any of my principles such as being adware.

The following is my opinion 😁

If you’re familiar with software development, for these apps the dev is the “product owner”: they have a vision for the direction of the app/project, the look and feel, the purpose, and the experience. The project is essentially no more than an incarnation of what that product owner wants, and they are likely the most active (or sole) code contributor. Without this product owner, the project can start to stagnate, deviate, or begin to make trade offs. In most cases, the project may serve as the product owner’s primary source of income. These projects are where you’d be supporting a developer

This kind of thinking doesn’t really fit into every project though, which is probably the perspective you’re looking from: e.g. Debian, yt-dlp, and various other open source projects that have a set goal or purpose, and guidelines/rules for volunteers on how to fit their contributions into this puzzle. There may still be product owners here, but things are much more democratic and open. A product owner, if present, may also have a much more hands-off role. These projects are where you are supporting the development itself