AliCoil practically useless to use a graphene if I'm still going to download such apps
This is not true. You can use GrapheneOS just like Stock OS with every privacy invasive app imaginable and still massively benefit from all its privacy and security features. Think of it like that: If you need to use privacy invasive apps, you want to use them on GrapheneOS because you have very powerful privacy and security tools and protections available there. Storage scopes, contact scopes alone already are a massive benefit for using invasive apps more privately.
You don't need to keep a "clean plate" in regards to apps you install if you use GrapheneOS. GrapheneOS is made to protect your privacy and security.
AliCoil different forums such as reddit
I highly advise against that. Reddit is not a good source for accurate or reliable information on security and privacy.
AliCoil I personally think even with such apps GOS is still good to use.
Absolutely.
AliCoil I haven't really setup GOS too hard so I factory resetted it since I can't be too bothered uninstalling every app, will go to a public space like you said and download play store there
On that note I want to also recommend you to use secondary profiles based on personas (like Personal/Work/School) and not based on app or usage categories (like FOSS/proprietary or Banking/Messengers/Social Media).
Most resources online tend to overstate the necessity of using profiles and often suggest setups that make heavy use of them based on concepts outside of personas. While profiles are a very powerful and amazing feature, they do not aid the app sandbox. They don't add any security to it. They block IPC and package discovery across profiles, but apart from that the app sandbox is the same everywhere. It is not safer to install an app in a secondary profile or private space than it would be to install it in Owner.
Profiles are not a necessity for a secure and private setup.
For most users the recommendation is to use Owner as their main/daily-drive profile, putting all their apps and Play Services (if needed) there. Then expand upon profiles for personas or if you want to specifically use their features. (like putting them at rest individually with a different unlock method, VPN slots, etc.)
Otherwise you are likely only going to heavily increase friction and decrease user experience while having no tangible privacy benefit.