U shouldnt really be cleaning the inside of ur phone with anything unless there is reason to do so like water damage/corrosion
If u do need to clean there are various PCB cleaning solutions available check the country ur in for what everyone else uses I.e lots of people recommend Branson ec liquid in the US for ultrasonic cleaning we dont have that here so we use an equivalent that is mixed with water the important part is to dry it thoroughly afterwards
To clean the screen u can use some isopropyl on a cloth or even window cleaner spray I like astonish lol however spray it on the cloth not on the phone be careful with too many chemicals things like alcohol do get under the screen if it's not fully sealed and will damage the backlight area.
Charging port toothbrush with a bit of isopropyl and headphone port a cotton bud with some of its cotton picked off dipped in alcohol.
Theres probably better methods for all of this I just make sure I get whatever I need on the part I'm trying to clean and no where else…