I would not put 1n4148 diodes in there, 2 of them anti parallel into 50 ohm is roughly +10dbm. While that not always destroy the TinySA it will be past safe limits. I would say 2 low capacity? diodes like the BAT45 or similar would be the better option. With it, the maximum power into 50 ohm is only about +5dbm
John Cunliffe W7ZQ