Dolphin Emulator is the most popular open-source emulator out there for the Nintendo GameCube and Wii, and it can actually handle the emulation job pretty well on high-end devices like the OnePlus 7 Pro or the NVIDIA Shield TV.
Rather than finding your old console from the basement to play your favorite retro titles during this lockdown, one could also opt for emulating them on their Android devices, provided they are powerful enough.