Very interesting. Had to hit Wikipedia to learn something about it. More or less an offshoot of the Araucaria family. Wikipedia mentions it can become quite stunted and dwarfed when growing at high elevation and or in nutrient poor settings. This bodes well for its use as bonsai.
On the down side, Araucaria species, such as the Norfolk Island pine are known to resist bonsai technique. But Agathis is a separate genus, its growth habits will hopefully submit or respond favorably to bonsai technique.
Agathis dammara is a unique choice of species and I heartily encourage you to experiment with it, and document the results.
You are allowed more than one entry into the contest. You are in Indonesia. There are some native species that have proven positive track records as bonsai. Look into the work of Robert Stevens, a number of the species he uses are proven bonsai subjects. Check out the genus Premna, and of course, you have locally native members of Ficus. Your locally native Diospyros (ebony family) might be an interesting choice.
Thank you for the encouraging words! I do have a bunch of other species in the works, although most are bought blindly online due to restrictions. If I manage to go up the mountains to visit some nurseries soon, I might have other more interesting species!
Diospyros Celebica, the Ebony tree which you are thinking of, was considered, but had a couple of strikes against it:
1. It is endemic to only one island which is not mine (although it is my dad's island...)
2. It is a slooow grower
3. It has huge leaves
All in all, I am very interested in growing it just for fun, but thought it would be against the rules (as well as my Eucalyptus deglupta and Pinus merkusii). I have considered Premna, Pemphis, Feroniella, and a bunch others (may revisit after lockdown), but I guess it's a case of choice paralysis hahaha.