The service is ok, but if you (rightfully) do not want to be tied to Cloudflare, take a look at Tailscale Funnels. Same concept, but from a company that values the user and their privacy. Also, for regular personal/small user base, free tier is more than enough. And you get a free .ts.net subdomain to use with your apps, if you need that.

Relevant Mr. Lovenstein comic: https://lemmy.world/post/8457726

Baby Shark. Because… it kinda looks like a shark? (Blue Mitsubishi Outlander Sport/ASX, depends on the country)

A laser, maybe, but definitely not LEDs. Vapor/gas lamps produce the narrowest frequency bands possible, because it comes from very well defined atomic transitions (Hz range). LEDs produce frequency bands with widths in the GHz/THz range, while semiconductor lasers can maybe reach KHz if they are really good. So, unfortunately, for this type of applications, vapor lamps would probably still be needed.

Source: I work with lasers and spectroscopy.

Edit: very good idea about using non-visible light!