Replacing 2 split receptacles with 2 GFCIs
Split receptacles are no safer it allows 2 separate circuits on 1 outlet. I have found a double pole GFCI to feed a multi wire branch circuit is more stable than trying to use GFCI outlets. If using GFCI outlets to prevent nuncance tripping each outlet would need to be GFCI using only the line or there may be issues if the load is used I have found a double pole GFCI circuit breaker is cheaper than a bunch of GFCI outlets. You would still have a separate 20 amps on each outlet but if any of the outlets sees a ground fault they all go dead, this would be the reason for individual GFCI outlets using only the line side and may be a good idea if your breaker panel is remote or if your fridge is on this circuit but it cost more. But no new wiring is needed with a double pole or individual GFCI outlets using the line only (feeding 1 hot wire through to the next outlet and alternate the hot to the outlet provides 2 circuits if you go this route)