Source-on-their-servers is the model.
Cloud SAST tools require your source on their servers to scan. Pricing scales with how many developers push code: the more you ship, the more they earn. If you can live with your codebase on someone else's infrastructure, a polished cloud product is the most polished option. Vulkro starts from the assumption that you can't.
Honest Where they win: IDE plugins from better-funded vendors are nicer. Vulkro has an LSP that works; the polish doesn't match.