You can do some interesting projects by leading the Raspberry Pi pins out through a 40pin cable.
Refer to GPIO Extension Board instructions for extending the 40 pins of the Raspberry Pi to a breadboard.
SunFounder has a very complete course system about Raspberry Pi GPIO learning kits, such as the following two learning kits.
This basic learning kit is suitable for the Raspberry Pi and Arduino novice. This kit teaches basic circuit design and introduces Python programming for beginners.
This is an advanced Raspberry Pi teaching kit that contains a robust array of components. This kit teaches physical computing and Python programming principles for beginners and advanced users.
Electronic Kit for Raspberry Pi and Arduino¶
United States: https://www.amazon.com/dp/product/B07QT78FXF
Da Vinci Kit for Raspberry Pi¶
United States: https://www.amazon.com/dp/product/B07WV2HYC6