The reason for my caution is that I have not tested the cameras that you are comparing. There are owners of those cameras on this forum who can provide a well informed view on their suitability for PCB work.
The T2L contains a decent imaging core called the Infiray S0. This will provide good PCB imagery but, as you say, it needs a host. The Infiray C210 likely contains the cheaper Infiray Tiny1 core, hence the price. The Tiny1 core may provide good imaging and I suspect it is to be found in the Uni-T UT260B, which provides good PCB images, BUT it has not been confirmed which core is in the C210 or UT260B.
If pushed for comment, I would expect the UT260B and C210 to produce useful imagery of modern small sized SMT components if used in the close-up scenario of 50mm or less. The use of a 20mm diameter 50mm FL ZnSe lens is likely needed for such imaging. The image will be in best focus at around 50mm distance and, unlike the T2L, you will not be able to choose your operating distance and then set the focus to optimum. In many scenarios the fixed focus lens system with supplemental ZnSe lens will work well.
I personally prefer complete camera systems that do not rely on a particular host hardware or software for operation. Android is a dynamic OS and future versions may prove troublesome to the camera software or the application could become obsolete. With a complete camera you have a working camera for as long as the electronics last. My exception to this ‘rule’ are thermal cameras that are specialist in nature and benefit greatly from using a host computer, such as in the case of the CA10. The computing power of a PC is used to provide the image analysis capability on a large screen. PC software is somewhat different to Mobile Phone Apps as I can easily choose which one I am running on the host to maintain compatibility for many years to come.
Fraser