probably not that you want to hear, since this looks mostly like a click add, soliciting opinions "on the site", but..
most of us, with tech background, tried to come up with a tech solution for "can't get my board" problem...
However, for most, the issue can be greatly reduced/mitigated by skill, low tech/cost tools and good practices:
- learn to bodydrag
-write your phone number on the board
- if new, use gojoe or inflatable kiddie arm floatie around the handle ($3)
- if surfing big waves - use leash (yes there are cases when it makes sense for advanced riders

)
- if you foil - the board usually tries to zoom downwind faster than you, so the only trick is to get it before it passes you

- make your board bright - $5 spray paint will do wonders..
- dont do anything funny miles from the shore and in silly conditions, unless other precautions are taken..
I did not lose a single board to a sea in the last 8 years or so, following above practrices (not the gojoe one

)
this is 1000s of sesions

Is there a chance of me losing the board? - the way I kite - always

Would I invest in a tech gizmo that would be more expensive than $5 spray paint or a plastic label? - hell no!

just a data point...