Selfhosted

So with almost zero knowledge about next cloud or even cloud services I have embarked on creating such a complex project. The idea is essentially involving a rpi 4 , ups power supply , a pendrive. For everyone I think that limiting gdrive storages are a headache along with that the data may not be secure. So I was thinking of building a internalized rpi hosted next cloud integrated server with all android and even laptop. So that I reduce dependency of Google for storing all my photos along with creating a secure environment for my data . I have basic knowledge of ssh and little bit linux but this , this is frankly uncharted territory. I severely need links sources and much experience in order to accomplish such a task . I'll be running along with this an encrypted program that will decrypt whenever I need it . The whole setup will be connected to my router wirelessly that will upload and download stuff to my rpi . Theoretically I really intend to include my own data to train my AI but currently I am faced with this problem . Thank you for hearing me out , I just need basic guidance nothing else