This is an interesting idea. Does Swissquote not perform the same US Estate Tax handling processes as IBKR?
My ETFs are not traded, so using SQ as a ‘holding pen’ for them would work for me. When I last used SQ, it was expensive in terms of fees and custody fees, but perhaps they have eliminated custody fees now. I wouldn’t want to pay for them just to hold it.
EDIT: If I read their fees correctly, I’d have to pay around 300 CHF per year per million in assets held. I think it would be better value just to buy life insurance instead, that way, if you die the insurance would pay out on death and bridge the time before the funds are released and in case of any estate tax, funds could be used to pay the tax too.