This guy's videos are trash. The whole PDF thing would have been solved in 2 seconds when he hit the Print menu and expanded the print preview which generates your pdf (i.e. print to PDF). From there, Markup-->send or save to files.
iPadOS needs work, yes, but the problem is people used to traditional computer systems (i.e. MacOS) are stuck in an old paradigm while younger folks and those without the need for things like external monitors or multiple drives or peripherals can get all their work done easily on an iPad Pro and then pull the tablet off the keyboard to kick back. Being stubborn and not willing to learn a new way of getting a task done doesn't translate to an inefficient product.
I'm in healthcare; my EMR is an app-first one with a crappy webpage UI. 100% of my work-related tasks are done on my iPad Pro. When I sit down on my Mac, it takes me double the time to do the task. Last week, I locked down a great new apartment and had to do all the financial paperwork and application work and got it done within an hour including generating all the proof of income, etc. that was needed. All done on my iPP without a single issue. I've been iPP-primary for years and the workflow is easy. Editing photos in Lightroom? More of a joy than my M1 MBP with the pencil in hand. I can keep going. Use the device that's right for you and ignore the clickbait.