A new connection 'isolated islands' was proposed, but I'd like to turn it into 'isolated WHS' (as the first would only be a secondary connection, not directly related to the WHS itself).
This as the complete opposite of WHS hotspots!

'WHS without any other WHS within a range of xxx kms'

Rapa Nui is certainly one. Gough Island another one. Others?
And where do we set the limited range? Rapa Nui is 3600 km from Chile, Gough 2700 km from Cape Town. So maybe, 2000 km to be able to connect a couple more?

If you set it too high you will only get island sites - could reduce or differentiate land/sea?. Is there a web site which quickly calculates Great Circle distances between 2 places given their Latitude and Longitude?

PS Easter Island is probably closer to Henderson Island than any site in Chile

Yes this site does the calculation
http://www.gb3pi.org.uk/great.html

Latitudes and Longitudes are on the UNESCO site

Henderson Island to Rapa Nui is 1914 kms (1189 miles) so - under your 2000kms Els!!
Rapa Nui to Valpariaiso is 3678kms (2284 miles)

Gough to Robben Island is 2600 kms (1614 miles)

There should be non-islands included too!
The Virgin Komi Forests are 1146 kms from the nearest other WHS, Kazan.
And SgaangGwaii 1104 kms from Nahanni.

So I'll set for 1000 kms.

Sgaang Gwaii is only 670 KM from Olympic National Park

Illulisat is 1500 KM from Pingvellir

St. George (bermuda) is 1200 KM from Independence Hall

Valle de mai is 1100 KM from Aldabra

Shark Bay is 1800 KM from Purnululu

East Rennel is 1070 KM from Cheif Roi Mata

Heard and Mcdonald Islands are 3400 KM from La Morne

Wrangel Island is 1600 Km from Kamchatka Volcanoes

Kamchatka Volcanoes is 1400 Km from Shiretoko

Thanks for your work, Xeres, in finding these out!