>reasonable switching PSU in an E27 lamp You can't have active pf correction for real in there (so pf would be 0.5). Pretty much all of them have bridge rectif

>reasonable switching PSU in an E27 lamp You can't have active pf correction for real in there (so pf would be 0.5). Pretty much all of them have bridge rectifier + capacitor. Most of them lack input filtering (common mode choke). The real issue is that even with the best light/power ratio, 2/3rd would be heat and that heat has to be dissipated. Electronics hate heat, even with full aluminium body, the light bulb requires plastic casing (as there is no earth available), so heat dissipation is heavily limited. Personally I have mostly near ceiling lights in the house. The non-dimmable/remote control ones would be fully repairable. For ones with the remote controls I can't replace the microcontroller as I could not copy the firmware but all the power driver would be fixable (the controller can be replaced with esp-32 and blue tooth dimming, though). Of course, for most people that would be an extra hassle and fully replaceable lights are likely better. However, custom designs allow for the most optimal heat dissipation.