Yes that is the point. The things you can do are more or less limitless and only restricted by the power of imagination of the builder.
Here in Colombia for example we have a material called Guadua . In your country they call it Bamboo.
People make rafts out of it - imagine it in combination whith sprayed polyurea sheets and the light rock material in the video above - it is quite obvious that you can do a lot of interesting things with that, when it comes to working on the watersurface, and make a first construction layer on it.
Althogh these natural segmented tubes have at least the toughness and strength of a similar sized aluminium tube - they are obviously not “code conform”. Do i now suggest to make a seastead out of bamboo ? Not really - but what the example does is showing that your selection and cost of materials you can consider to use in your composite structures also widley depends on your local supply situation . ( Guadua costs next to nothing here ) While you would consider a ice sheet as first construction layer in Canada (Habakkuk ice ship), you will consider a bamboo composite in the tropics.
In the “poor man´s floating island - project” we took a somewhat different approach of combining materials to a floating island of “lowest possible cost”, to give poor people floating homes in the floodplaines of the Magdalena river (Government investigation project). This approach depends on a form of “material supply” that is “non code conform” in your country, but very doable in other parts of the world from India to South America.