South Africa Salvador & Uruguay Any Gems?

These are the last 3 countries I have that I'm basically posting for general info for friend. His concern is any hidden gems as they are pretty well sold but he's affraid of giving away something with really high value. Let me know if you spot anything that would be worth a second look . Some interesting honeycomb like watermarks on the Salvador but other than that and the $2 value I don't have a clue. Thanks for any and all help as always.

A couple of interesting postmarks amongst the South African stamps here nitrolures.

South Africa Used in South West Africa

The first stamp in the top row features the rare 'WINDHUK' cancel with 'P' of 'S.W.A.P.' at the base removed (the canceller had been prepared with South West Africa becoming a Protectorate in mind). The cancel was used for a little over one month (6 JAN 21 to 15 FEB 21). On this example the 'N' of 'JAN' can clearly be seen. This is a scarce cancel.

The third stamp on the first row features another Windhoek cancel, this time the most common converted German canceller. The oval German Swakopmund-Windhoek Train canceller (withdrawn by the Germans from use in 1904) was modified (Swakopmund removed) and introduced by the occupying South African forces in March 1916.

In the second row, the third stamp features a partial but distinct Swakopmund cancel - from another converted German canceller. Being a partial cancel, with only a fragment of the date, it is impossible to determine which sub-type it may be.