: An open-source, cross-platform alternative to Odin that works on Mac and Linux. Recommendation

Zero. Check Google Play: no such app exists because Google prohibits it.

Why (concise)

. It needed high-level system permissions to write directly to the device’s internal partitions like the kernel, system, and modem. The "No Root" Mirage

Always check comments. You will see real users saying, "Doesn't work on my S21 Ultra. Just says 'No partition found'."