I do not believe that covid was intentionally designed and released as a bio weapon.
That being said, have you heard of long covid?
Why should I believe this is any more real than "chronic lyme"? There are a whole lot of hypochondriacs out there; something proponents of "long covid" and "chronic lyme" never seem willing to acknowledge.
The groups promoting both of these organize and operate the same way, and make similar claims. Huge lists of nonspecific generic symptoms and facebook groups full of uncritical believers mutually reinforcing each others' beliefs (parallel to the well understood phenomena of "support groups" which promote eating disorders and create social feedback loops for reinforcing/worsening body dismorphia.)
History says you are wrong to discount NATO countries (I include Japan as an unofficial member) using bio-weapons. They have a long history of deploying and supporting deployments of these kinds of weapons against military and economic foes.
The number of people with long COVID symptoms is a tiny tiny fraction of those exposed to SARS-CoV2. If it's a designed feature of SARS-CoV2, it's very poorly implemented, unless it's actually very specifically targeting some as-of-yet unidentified demographic. (This seems very unlikely.)