The US labs should be investigated, just not from the incompetent buffoons of WHO, whose fake investigation of COVID19 origins has turned up zero new information.
Worse viruses are already guaranteed. The broad reach of COVID19 means it will be co-infecting cells forever (including dozens of species), and when it shares an infected cell with another virus they will swap genes attempting to create a new super-virus.
The public is unaware how many natural mechanisms there are to swap genes and produce recombinant organisms. Viruses swap genes with each other and with their hosts, bacteria have a mechanisms to open their cell walls and swap genes with their own and other species, and COVID19 infected human cells can tunnel through the cell walls of their neighbors in a similar fashion - so it seems to be a feature of all life.
The shiny new tool of genetics researchers was not an invention but a discovery. CRISPR is a naturally occurring gene splicing enzyme, and there are viruses whose MO is splicing host genes.
Nature has been running septillions of gene mutation experiments per second for the last 3.5 billion years, and through many extinction and near extinction events has achieved a dynamic stability where suppression of genetic change balances all these genetic change modalities. The dynamics change during environmental stress including competitive stress, climate change, etc. which increase the rate of mutation and re-combination.
Humans are now causing mixing of the gene pools in new ways that circumvent Nature's checks and balances. This is what makes genetic engineering, and even labs collecting genetic samples, inherently dangerous on a scale beyond chemical and nuclear weapons. Gene mods can't even be tested for safety in the same sense as a new machine or non-reproducing molecule.
A human created genome can swap genes that were previously held static by unseen forces, and create a Frankenstein pathogen decades after release into the environment, many orders of magnitude beyond conceivable lab based testing and statistics (in vitro) or even field trials.
Just look at the evidence in medical molecules. As a rule, all new pharmaceutical formulations decrease in efficacy and increase in side effects from clinical trials to commercial sales. This is because even tens of thousands of test subjects is too small to "scientifically" predict the response in a world of 8 billion humans in all their genetic, epigenetic and environmental diversity. The response to new genetic combinations is far more complex and potentially dangerous.