In both cases, you're getting a whopping $300 off the normal selling price. The only thing you have to keep in mind is that you need to activate service on Fi within 30 days of your purchase.
The discounted price will automatically apply during checkout, but if Fi is not activated in 30 days from the device's shipment, the discounted amount will be charged to your Google Payments account to match the full price of the handset.
The good news is that there is no minimum activation time needed to be eligible for the deal. On the other hand, activation must be full service (so this doesn't apply to a data-only SIM). Obviously, the offer applies to US residents only - which makes sense since Fi is only available there. Finally, keep in mind that there's a limit of one discounted LG phone per customer.
I really think they should drop the ThinQ name. If you agree with me, ThanQ! :P
Now its the time of the year to dump all sd845 chipsets to market for whatever price they might sell. Xiaomi is dumping their stock with pocophone and all other brands need to react to it or they will not clear their inventory of sd845 ever. Glad to ...