MajorVape: I'm not sure I understand what you refer to as "pressure" from either traditional tobacco, emerging independent vaping product manufacturers, or the major US tobacco companies who have entered into the vaping market sector. I was delighted to see the major, former exclusively combustible cigarette manufacturers- including those that employed me throughout my career- develop a serious interest in offering potential reduced-risk vaping, lozenge & pouch products. The writing was on the wall- combustible cigarette use was in decline due to the well-documented public health burdens & growing social stigma that accompany cigarette smoking.
I can honestly say that I never experienced any sort of pressure to fight or resist this natural evolution toward safer nicotine products. I've always been free to express my scientific opinions as an inhalation toxicologist in support of tobacco harm reduction throughout my working career.
The more profitable manufacture of traditional cigarettes was the financial engine that enabled the initial start-up R&D investments of multiple $millions of dollars required to produce novel vaping products that could pass muster to receive marketing orders under the new & highly restrictive post-2009 US FDA-Center for Tobacco Products' regulatory paradigm. The emerging vaping products companies like Juul and others made some missteps early on, but have largely learned how to do business in the Brave New World of US tobacco/nicotine regulation. The FDA-Center for Tobacco Products is also in a steep learning curve in figuring out how to best fulfill their tobacco regulatory obligations. All involved in the equation have a fundamental interest in reducing the adverse public health consequences of cigarette smoking.
The responsible, major US vape manufacturers invested the tens of millions of dollars required to perform the necessary human clinical biomarkers, behavioral, and large population survey studies to obtain marketing orders from FDA for their cigarette-alternative products.
The small, independent US vape shops and minor manufacturers typically just didn't have the necessary financial or scientific resources to perform the needed studies, and FDA has stated that it has issued Market Denial Orders for something like 99% of those submissions from minor manufacturers & shops. I realize that many/most Forum members here are enthusiasts of the later-generation open systems, and at this writing these are continuing to be available at vape shops here in the USA- but FDA enforcement actions against them are ongoing. In the coming years I think many of those options will be removed from the market here.
The open systems pose a very difficult regulatory challenge for FDA, which considers any combination of particular device hardware with a particular e-liquid to be a specific "product". A shop offering 4 hardware devices and 100 e-liquid options is regarded to be a "manufacturer" offering 400 different products- each requiring a separate pre-market tobacco product marketing application [PMTA].
The US FDA lacks historical experience in regulating products that are neither nutritious, efficacious, nor "safe" in an absolute sense, but instead apply a nebulous "appropriate for the protection of public health" standard in regulating new tobacco & nicotine products. In essence, getting a Marketing Approval Order for, say, a novel vape product requires a sound science-based data package that demonstrates that a particular product is less harmful than a conventional cigarette in terms of both individual user risks as well as population-level hazards.
That might sound like an easy standard to meet, but detailed scientific evidence for the specific product of interest, and not just published evidence for e-cigarettes generally, is what FDA has required to date here in the USA. There are certain data-bridging strategies that may be used to advance a product with something less than a comprehensive, $10 million data package toward a Marketing Order, but they require contributions from well-informed scientists that most small vaping interests simply do not have at hand.
[As always, these are all my own personal opinions, and not those of any other person or organization.]