I have recommended this book to any new PI that I meet. He draws diagrams for mobile and static surveillance techniques that will be awesome for you in workers comp.
You don't need tens of thousands anymore. In 2010 you could make your own and it would cost ~$1500. Now it's less than $1000, and could be substantially less depending on the hardware choices you make:
http://hackaday.com/2014/07/05/a-gsm-base-station-with-software-defined-radio/
I've used this one for years and PI's I work with use it too. Very rugged, easy to use and does the job well.
I've heard good things about these: https://www.amazon.com/dp/B097ZQDYDQ?aaxitk=3e635082b7eac43e32ee3902046ad251&pd_rd_plhdr=t&ref=dacx_dp_6923870940501_586404641573099535&th=1
I wouldn't worry too much about the memory card thing. I use iPhone footage in court all the time. A digital copy is a digital copy.
Could be a monocular with an infrared light. The size would match up. Many of them can record video, which would explain why he seems to hold it at waist level then tries holding it steady (i.e. trying to get a view of someone's house/vehicle, confirming plates, who knows).
I'm really at a loss for what else it could be. The thoughts of a cigar/cigarette, vape pen, and laser all crossed my mind but none of those really add up.
If he does this consistently, might be worth dropping the dough on one yourself and doing a little counter surveillance haha.
You may want to do a domain spam check and file an appeal with Google support with some test emails. If your domain is a G Suite/Google Apps account, the domain administrator usually has access to 24/7/365 support from Google - see this page
This one! I reference it fairly often in my daily activities.
Open Source Intelligence Techniques: Resources for Searching and Analyzing Online Information https://www.amazon.com/dp/B08RRDTFF9/ref=cm_sw_r_cp_api_glt_fabc_2YYEEK87E398F1R3BSXS
This isn't a bad little book at all, despite the goofy title
https://www.amazon.com/Complete-Idiots-Guide-Private-Investigating/dp/1615642501
Not sure if you really need a CAD type program but Amazon, (I'm in Canada so the link is to the ca site) but you can find a variety of stencils for crime scenes, traffic accidents, etc. They also have all the architectural ones as well so you can draw on the fly quickly without having to lug a computer around.