"And because of the U.S.’ perceived financial strength, there is also a large appetite for U.S. Treasury bonds (otherwise our government would not be able to spend the way it does)."

This (wrongly) assumes that the monopoly issuer of our currency needs to "get" its own currency from some other source to enable spending. This is at the core of most misunderstanding of the federal government's role in the economy and the source of fear surrounding the dollar's future. Unless you can explain how one can collect (tax) or borrow (bonds) what doesn't yet exist your assumption that taxes and bonds "fund" spending at the federal level fall short.

Until the government spends its currency into existence in the private sector there is nothing to tax or borrow, so neither can be "funding" mechanisms. Both taxation and "debt" remove excess reserves from the system and spending increases those reserves. The reserves created by the government are the only source of "net" monetary assets in the private sector that can "net" retire private sector debt or be "net" saved as a store of value in commerce.

All bank activity nets to zero below the level of money creation and requires a constantly expanding economy without deficit spending sufficient to retire private debt in a timely manner. The national debt that everyone thinks we should pay down is nothing more than an aggregate of all net money in the economy after private sector debt is balanced against reserves.