Sega Master System / Mark III / Game Gear
The scroll locking bits are still effective but, in GG mode, the top two rows are off-screen (so horizontal scroll lock is not visible). The vertical scroll lock is partially on-screen, giving two columns of visible scroll locking.
The leftmost column is also off-screen so there is no use for disabling it.
The sprite limit can still occur for off-screen sprites; thus, it is important to avoid displaying sprites off-screen to avoid this.
Differences between SMS and GG are noted in relevant sections where applicable; anything GG-only can be mentioned here.