Sorry, but you have totally missed a few things:
- how much gain and power output capability is needed for decent guitar amplification
- how transistor amplifiers with the needed capablities are constructed and how they function as circuits
- what amplifier's speaker impedance rating mean
If an amp is rated for 8 Ohm speaker, inserting for ex. 4 Ohm speaker can cause overheating in the amp and having more, say 16 Ohm gives less power and can also cause instability, if the amp has an output transformer like tube amps generally have.
With 2N2904 you can construct an amp which outputs theoretically 300 mW. It's a common emitter amplifier stage with about 3,5V operating voltage:
This circuit wastes continuously DC power as much as it can output, its so inefficient that I do not recommend to build it except a a test for "have you learned enough of the math of basic electronics to get the parts calculated right"