As several models are mentioned I’m not sure which radio you’re talking about.?
With my QCX+5W I installed a small 40mm dia 32ohm speaker in the case and connected it internally to the negative and ‘No-plug’ output on the earphone socket?
Not only was it plenty loud I had to add another 47ohms in series to stop the CW rattling it at max volume?
32 ohm speakers are a bit rare but I suspect 2 (or 3) small 8ohm speakers in a small box (wired in phase) would be equally loud if plugged into the earphone socket as an external speaker?
Bruce Akhurst