(please take a look) help with firebase database rules

i want to make an app that everyone have profiles.

like this: i created an account with firebase auth and added profile details like bio, social account usernames etc
then you searched my username in search layout and retrieved my profile details and followed or wrote a comment etc

my old logic was as follows: the user registers and a unique id is generated. A new sub-database is created with that identity and the user’s information is stored there. also the username and the user’s id are stored and when someone searches by username the user id is retrieved and projectBucket is set to that id. and then access to information is provided. I did this but i want to remake with secure way. before rules was read true write true. I tried that but i dont know if its works like wanted: