yoyoma Taping mics is absolutely useless. For starters, if you are afraid of an adversary using mics consider that dynamics can also be used to record audio. And even so, even if you tape up the mics or dynamics (which is just gonna distort audio a lot) or even go for the novaphone where they are outright removed then the problem is still that gyroscopes and accelerators can be feasibly used to record audio as well. If you somehow manage to remove them, then sure go ahead, except it won't be a particularily useful phone unless you only plan to use it just for like reading stuff.
In cybersec a very important concept is the concept of trusted and untrusted parties. Of course minimising trusted parties is important but at some point you gotta trust the people who build and ship the phones and the Graphene devs at the very least. Weighing your priorities is a part of what makes it so hard, so at some point you need to consider the positives of no one ever potentially conducting an attack the chance of which is highly unlikely at best vs having a usable device. I hope you can find a solution that suits you.