My current WFH setup includes a Manfrotto 244N magic arm attached with a RAM mount to a Rokform RAM ball that very securely attaches to my Rokform iPhone case. It's clamped to my desk with a Manfrotto 035 SuperClamp. The RAM adapter is P/N RAP-B-366U and the double swivel on the RAM side is a RAP-B-201U . The Rokform part is "Universal Ball Adapter Phone Mount" SKU: 337101

RAM also makes a great iPad "X-Grip" holder, along with tons of different mounts for different situations, especially vehicles and things like exercise bikes (e.g. look for stuff like a "RAM® Double U-Bolt Ball Base for 1" - 1.25" Rails" or indeed their actual handlebar mounts). These are sturdy, pro-level mounts, not the cheap disposable junk from no-name brands on Amazon.

For my Zwift stationary bike setup that I use my old road bike on, I just use a $15 Niteize Handleband to attach my phone plus a Vornado 783DC made-in-USA DC brushless fan to keep the sweat levels low.

Another couple brands worth checking out would be Joby's stuff (I have an old GorillaPod DSLR that holds my webcam these days) and "The Joy Factory" who make pro-level iPad clamps / stands.