This is a bit of a “how long is a piece of string” question, security is multifaceted.
From what I understand, it uses your phones kernel, so if its out of date or vulnerable, that might be a problem, and you may not be able to fix that.
Conversely, its running inside android, so the android hardening might make it more secure.
What are you specifically concerned about? Firewall? Zero days? Antimalware?
Still a bit open ended. Web browser finger printing is probably going to be quite specific, unless you have a browser that avoids fingerprinting.
There is a trust issue, you need to trust the userland packagers to not build in any additional tracking, but its pretty unlikely that they’ll do that given its a tiny project.
Privacy is also multifaceted, and its never going to be as simple as “use this distro”. The techniques for online tracking are changing and evolving all the time.