[Blink]

The only on-device rooting app that works consistently has been Kingroot/Kingoroot/Kingoapp in my experience. The issue with it, is that its closed source. On-device root exploits are literally just priv-esc exploits, and should be patched ASAP. With open apps, they allow Google to patch the vulnerability, and help the community, but closed ones prevent that (you can always try and RE it though).
On-device rooting tools are dangerous for both the community and users.