I’m not the type to put my dotfiles in git, though.
That's what I'm saying, you don't have to! Just install the package (like neovim or whatever) through NixOS and it will use your ad-hoc dotfiles like it would on any other distro. For a lot of stuff you can make use of declarative NixOS options (programs.neovim = { ... };), but you don't have to, except for really basic system stuff like networking I guess.
Pre-compiled, non-system binaries.
Gotcha. There's several ways do do this on NixOS (steam-run works like a charm!), but I'll concede that there's an extra step involved here that you don't have to do on other distros.
That, and seeing talk about how great Nix is but also people having trouble later on too (major updates? bleeding edge woes?).
There's a learning curve for sure, but I haven't looked back or experienced any major issues (where I hadn't shot myself in the foot) since 22.11.