The architecture is described enough to re-implement it and train it on known datasets/benchmarks such as VQA2. A single man with a medical degree named Phil Wang ('lucidrains')[0] has the ability to reproduce most of these papers by himself. He has 246 GitHub repos[1], most of which appear to be reproductions of models which are only described in papers that had no associated code or models released, such as [2]. Often it appears he releases code within 2 weeks of a paper's publication on ArXiv.
0: https://lucidrains.github.io
1: https://github.com/lucidrains
2: https://paperswithcode.com/paper/coca-contrastive-captioners...