Researching in the morning after coffee leads me to believe these sort of structured products would be considered "Exchange traded notes" (ETN). According to two sources
<<An ETN offers a tax-efficient way to invest. It is treated as a prepaid contract (such as a forward contract) for tax purposes. The buyer of a prepaid contract pays an initial amount in order to receive a future payment based on the value of an index or other underlying benchmark at a specified future time.
Very often index mutual funds and ETFs are required to make yearly income and capital gains distributions to its fund holders that are taxable. When a fund is forced to sell stock to rebalance or otherwise change its composition, the fund holders have to pay any resulting capital gains tax.
With ETNs, in contrast, there is no interest payment or dividend distribution, which means there is no annual tax. Capital gain (or loss) is realized when an investor sells the ETN or it matures. Long-term capital gains are treated more favorably than short-term capital gains and interest in the US (> 1 year holdings are taxed at a capital gains rate of 20%). There is no way to avoid paying capital gains tax, but there can be great advantage in wealth building by delaying it.>>
Here's what Fidelity say, for example:
https://www.fidelity.com/learning-center/investment-products/etf/types-etfs-etnsand Barclays say the same thing.
So seems to me like FBAR, 8839, then capital gains tax on sale.
I've seen other resources which say there is no final decision yet - so what's one supposed to do when filing taxes if the IRS haven't decided?!! I suggest one takes a position and documents it.
A