The Kiwi Browser at Google Play currently mentions as of Mar 20, 2023:
- Updated Chromium to 107.0.5304.66.
... whereas my distros Chromium is currently at 111.0.5563.110 via snap. Chromium itself is probably at an even newer revision. None of this necessarily means it's "bad" but it does mean it's behind the current security patches.
Anyhow... you tell us if it works natively or if you need a .user.js engine. I would suspect it needs a .user.js engine like Tampermonkey (TM) or Violentmonkey (VM) like most Chromium based browsers (there are exceptions to this).
According to jesus2099, the program Kiwi Browser has userscript support.