archbtw
apart from laggyness
There's no such issue with GrapheneOS. If you don't like the added time for cold start app spawning and extra memory usage needed with secure spawning, you can choose not to use it. It's an optional feature. It's important for privacy and security but it makes far more sense to turn it off than using a non-hardened OS which has never provided comparable privacy or security features along with not ever keeping up with privacy/security patches properly.
I will be taking the lineage apps, changing the package name and compiling them, so that I can install them on graphene safely without package name conflicts (stuff like dialer, alarm app, etc).
You can use those apps if you want and nearly all will work fine. There are lots of other alternatives available.
Is this going to harm the security in any way? I don't know which graphene apps are hardened. I assume the sms app has some additional protections? I would rather not want to change those apps.
We can't vouch for the privacy or security of LineageOS code in general.
Messaging has some improvements in GrapheneOS but we haven't done a lot yet. It's in-progress and going slowly right now, as is overhauling or replacing the others. We have far higher priorities.