Tough ask to get the no visible fixings. Magnesium oxide board (see the INEX brand) would give you the light coloured look, sheet or boarded look. The product can be painted but looks great raw too, has a shiny side and a striated side so you can have a variety of looks. Good luck

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If you have a boat , you can launch it in bigreaders 'arbour hahaha . Wood toned , or real wood window frames would add to it IMO -- that 3rd house that you like ( so do I ) , you see how the timber gate is so simple , but takes it from being a 'white box' to being a beach theme . And like you , i would be mildly worried that the right side will look a bit plain , especially as it will be very similar to the garage side -- that was why I suggested actual bricks . The windows , even if in white or black , are quite 'interesting' in shape , but being symetrical and flat that wall may look a bit 'meh' . To do one side white , the other in say a surfmist ( a slight blue tinge ) may look too try-hard too , but maybe do that 'righthand' side in weatherboards ? Keep it simple , paint it exactly the same as the rendered walls , but it will not look the same ? Also , weatherboards where what seaside cottages were traditionally constructed of , so there's that tie-in there too . Just throwing ideas around . And on a complete side note , I can't understand the logic of no brick walls -- I assume it is all new-builds , and brick adds variety and interest , its generally warm and IMO attractive -- just my preference , but I prefer some brick as opposed to an all render look .

Hebel is great for insulation but needs to be rendered and painted so more labour means cost was similar to brick and Hebel is susceptible to cracks along joins and damage from bumps and paint and render stains while brick is virtually maintenance free so would not use Hebel or any cladding that needs to be rendered or painted again... "next time" we plan to use well insulated reverse brick veneer clad in galvanised steel to maximise passive solar energy in our cold climate but gal roof and walls not acceptable to some councils and heavy walls not suitable for hot climates and very interested to hear others' experiences comparing traditional brick with other cladding