I'd also advise caution with Graphene. At best, the founder's a dick who harrasses anyone who's critical of his behavior. At worst... I honestly suspect that Graphene may be an op. It currently appears secure, but it's very weird how it's getting this reputation forced on it of being "hated by cops" and "the OS of choice for crimimals," especially when suggesting basic security features found in other OSes gets people banned from the github by the founder himself. It's only officially supported on new Pixels (the prevalence of the Google Pixel in the alternative, security-focused OS world is frankly concerning) and the founder has harrassed vendors for selling older, more affordable phones with GrapheneOS (the security concerns of older devices are valid, but poor people deserve more secure phones than Google Android too). It came out of nowhere and rose to the top based on a rather contrived reputation that was heavily publicised. It smells sus to me and would not surprise me if it turns out the founder is working for the feds.
And before you say "but the founder stepped down (after harrassing several big names in the digital privacy world)," who "replaced" him? The answer is himself. He moved stewardship to the GrapheneOS Foundation. The dev directors are chosen by the members of the GrapheneOS foundation. The foundation has only one member: the founder/"former" lead dev. The "former" lead dev is one of the 3 directors. There are two lead devs now and the wording of the announcements (almost certainly the founder writing) strongly suggests that one of those two is that same guy and one of the other directors is the co-lead, again chosen by the founder. Previous announcements of stepping down were deleted. He talks about combating misinformation while spreading misinformation himself. Fed behavior.
Absolutely root your phone if possible and put an alternate OS on it. Look into your options, but I'd be very cautious with GrapheneOS. Even if it's not actually fed shit, the founder has a history of harrassing people for being critical of his behavior and has banned at least one person from the github for politely requesting a very simple security feature that exists in other OSes which is not a good sign for the future security of GrapheneOS.
For some other alternatives:
iodéOS - Fork of LineageOS
/e/OS - Fork of LineageOS
Ubuntu Touch - Ubuntu Linux for your phone/tablet
postmarketOS - Based on Alpine Linux (for "power users")
PureOS - Linux-based. Idk shit about this one.
Mobian - Based on Debian Linux
CalyxOS - De-googled Android. Lineage uses some Calyx apps for some of its features. (WARNING: Releases currently on pause til further notice)
I only know surface-level stuff on all of these, so do some research before choosing one. LineageOS is probably the most popular alternative besides GrapheneOS, but it's important to look into these things yourself before choosing one and listen to the techie people in your life. Looking into GrapheneOS beyond the hype is how I found out that the lead dev/founder is hella sus.
(As a side note: if you have an Amazon Fire tablet, it is Android based. Depending on its age, you may be able to root it as well.)