You linked to articles describing actual biology, not anything like "Chi".

I pointed you to the mapping of the concept of Prana/Qi/Chi/Ki in today's scientific context. They were framed in a different cultural context with a different concept of "Science" and it is up to you to map them to concepts in modern science.

For example they had a different model of Anatomy/Physiology in spite of the fact that they were aware of the various circulatory and nervous systems. Their approach was more holistic and empirical rather than reductionist and analytical. So even though you might not have a one-to-one correspondence to concepts in modern science there is enough studies/research done to establish that there is something to those ideas and hence their various practices (especially Yoga and Acupuncture) are now used in Healthcare to treat various ailments.

Some resources;

1) Perception of Subtle Energy “Prana”, and Its Effects During Biofield Practices: A Qualitative Meta-Synthesis - https://pmc.ncbi.nlm.nih.gov/articles/PMC10498708/

2) The Science of Tai Chi and Qigong as Whole Person Health-Part I: Rationale and State of the Science - https://pubmed.ncbi.nlm.nih.gov/40091656/