--- While your point is completely fair in that 24 packages won't make a very useful service, it's also fair to say this is a new tool and it's OK to give it some time. --- (EDIT: for the sake of transparency, I'm crossing out this initial paragraph since, after reading some other comments, I've discovered that cppget isn't all that new; the rest of my comment, however, is relevant without that statement)
I'll poke a little at your assertion that it's "never the build tool itself". Unfortunately, in my experience, it often is. Have a nice fight with Hunter in a project or two. It's got a decent, though still somewhat small, number of packages[0], but that doesn't make it useful. Every time I reload my PC and clone the two repos that rely on it, I invariably spend a day sorting out something or another (last time it was signature related). It doesn't help that the tool is tied to CMake, these are the only two repos I use that rely on CMake and I have actively avoided learning enough about it to not require several Google searches when I need to do somewhat simple things, but that's the rub. Cargo is simple, even npm (by comparison) is simple even for projects with great complexity[1]. Hunter, by comparison, has me asking every single time I have to update a dependency or install fresh from a clone ... what problem is this solving for me? How is this less manual than managing dependencies with a clever zsh script[2]?
As far as vcpkg is concerned, I agree, though I'm a Microsoft fan[3]. It generally works -- and unlike Hunter, which uses CMake as well, I haven't run into the kind of hair pulling, four-letter word spewing fits using it ... at least not to the extent that I did.
To the authors: Really, though, please please keep investing in making better dependency management tooling. If it's good enough, there are enough of us that will make "unofficial packages" because it takes less time to figure that out than it does to figure out how to fix the broken dependency management system we're stuck with.
[0] https://docs.hunter.sh/en/latest/packages/all.html
[1] I'm certainly not saying it's not without its pointy corners, but I'll take those sharp edges any day over some of the C++ build tools I've played with.
[2] Which is the only "build dependency management" system that's worked for me -- I literally "lynx --dump" the releases page, parse for URLs, download and script out each build dependency manually ... I even have a set of functions that manage to do some of this in a relatively well abstracted manner given the circumstances. Granted, these are single platform target apps, but so are the handful I have that use vcpkg.
[3] Well... to be fair, my one Windows 10 install is in a virtual on an openSUSE Tumbleweed installation, so maybe I'm not a fanboy, but with their movement towards open sourcing a lot of their tooling and frameworks, there's not a lot I can complain about, personally.