I wouldn't exactly trust Dalgleish to be impartial on this issue, during the height of the pandemic he lobbied for certain companies to be given contracts for the vaccine whilst holding shares in those companies plus he has repeatedly claimed that organisations that have disagreed with him are controlled by China, to the extent where he tried to get the UK government to spy on certain scientific organisations. Bearing in mind, he has also previously worked with right-wing lobbying groups and was a UKIP parliamentary candidate in 2015, I would say he would be very biased.
Plus John Campell has a reputation for spreading misinformation on his Youtube channel, and would never be my go to source.
It's one very complex, multifaceted theory, something that hasn't properly been disproven but also hasn't been 100% confirmed, and within that theory there are disagreements on if it was accidental or not, the intentions behind it and collaborators.