Here’s a simple 1 transistor amplifier that will amplify the voltage to a decent range not just line level 1v. I found it in falstad, Falstad had the specs I wanted. A oscilloscope may be good to have to check voltage levels and signal quality. I used ceiling fan capacitors the output capacitor was 5uF but works the same at 10uF probably the more output capacitance less ac resistance you get. I used a 2N3904 as the transistor.
This type of amplifier is called a “Common Emitter Amplifier” Note that this amplifier won’t give you a lot of current like a real function generator
Circuit Simulator