If the connections are screw connections with ring terminals then I would undo them, clean the actual mounting surfaces and apply the No-alox on those surfaces including on the screw threads. The No-alox will keep out moisture/air and itself is conductive also acting as an antiseize for the screw.
Even if the wire end is only clamped to a fitting those surfaces need to be cleaned and proected. In this case the wire end should be tinned heavily. This connection is not the best but sometimes cannot be avoided .
Once done then a spray could be used to help. But personally if there is a question about the connections then take them apart, clean, goop them up and then use the spray as a mtce. item helper.
{In freshwater moorage} Are you referring to the silver-silver chloride cell electrode use? It will not give the same readings as in salt water. In brackish,mixed salt/fresh water I do not think you will get a good reading. However it will still tell you if a piece of metal is connected or not especially when compared to other pieces protected by the same zinc.
If the bonding system is all connected the voltage should be the same on all the pieces connected to a particular zinc. So if you have one of the large transom mounted zincs all the pieces should show the same voltage or very close. If not then there is a bad connection between the zinc and that piece of metal.
Verdigris, that green colour, is normal from copper oxidation and on the metal part doesn't usually need to be concerned about unless very heavy. However, if it is forming on the terminals and screws that secure those terminals to the metal parts to be connected, then yes, be concerned. If the verdegris grows under the connection then it may interfere. The only metal I know of that the metal corrosion byproduct is still conductive is silver. All other metal corrosion byproducts are poor conductors. Maybe gold also.
Just a point that if there is verdegris growing then take a look at the seals on the hoses, connections, pipeing joins, etc. Normally just being damp will not cause much verdegris. Some spots but no heavy coat. It will grow and be persistent if the bronze parts are wetted often in which case as time permits take a look at resealing those pieces.
Bronze strainers and stuffing boxes can be difficult as they invariably get wet. But other fittings such as seacocks, unless old rubber plug Grocos, should not get a heavy coat of green, particularily not quickly.
