Design / Architecture for many instances OOP (or another) implementation

We want to write an API (Python Library) which provides information about few systems in our company. We really aren't sure what is the best OOP approach to implement what we want, so I hope you'll have an idea.

The API will expose a series of tests for each system. Each system will be presented as a Class (with properties and methods) and all systems will inherit from a base class (GenericSystem) which will contain basic, generic info regarding the system (I.E dateOfCreation, authors, systemType, name, technology, owner, etc.) Each system has many instances and each instance has a unique ID. Data about each system instance is stored in different databases, so the API will be a place where all users can find info regarding those systems at once. These are the requirements:

1. We want each user to be able to create an instance of a system (SystemName Class for example) and to be able to get some info about it.

2. We want each user to be able to create multiple instances of a system (or of GenericSystem) and to be able to get info about all of them at once. (It must be efficient. One query only, not one for each instance). So we thought that we may need to create MultipleSystemNames class which will implement all those plural-approach methods. This is the most challenging requirement, as it seems.

3. We want that data will be populated and cached to the instances properties and methods. So if I create a SystemName instance and calls systemNameInstance.propertyName, it will run needed queries and populate the data into propertyName. Next time the user will call this property, the data will be immediately returned.

4. Last one, a single system class approach must be preserved. Each system must be presented as a sole system. We can later create MultiSystem class if needed (For requirement 2) but at it's most basic form, each system must be represented singly (I hope you understand what I mean).

The second and the fourth (2,4) requirements are the ones that we really struggle to figure out. Should we use MultiSystemNames class for each class and also for GenericSystem (MultiGenericSystems)? We don't want to complicate the user and ourselves.

Do you know any OOP (or another) best practice clean and simplified way? Have we missed something? I'm sorry if I added some unnecessary information but I really wanted to give you a feel about how we want things to be.

If you've reach so far or not, thank you!