You should read about relatives trying to help victims of romance scams on reddit /r/scams. Generally its hard or impossible to convince some who is emotionally invested. I recommend you point out past BTC volatility and drops, and suggest he diversifies a bit if that's all his savings. He could put some in gold, some in shares, leave some (maybe 50%) in BTC. He will still win big if it "goes to the moon", and will have some protection from a crash. Often you need to make a mistake before you can learn this lesson. Eggs in baskets.

The first 3 letters are unique for the English seed words, so you just need to encode 25*3 = 75 letters.

I also think it is worth writing them down in a way that is not obviously a crypto address. You can place 75 letters in a 9x9 square (with maybe some extra dummy letters) that looks like a common word puzzle, eg sudoku or crossword, in a specific order, eg a spiral. You can custom print a template or copy one from eg https://puzzlestream.com/sudoku/blank-grid.php .

I currently use newpipe-sponsorblock on f-droid, which looks like a precursor/sibling/fork from tubular

The US dollar has lost about 98% of it's value since 1971 yet people still use it in trade rather than gold or silver or a better fiat like Swiss Franc. Don't underestimate the power of inertia. Just because USD has inflation problems doesn't mean XMR is about to take off. It will take hyperinflation or a currency crisis and even then better-known cryptos like BTC or LTC will be the first choice for normies.

Sure there are some extremists in almost every political faction, but were his comments denounced by others in his party?

I'm curious how he passed on the seed words to you. Did he write it down, give you the password for a password manager, put the info in his Will, transfer to your wallet address, or give you a hardware wallet? Did he just trust you with access to his computer data before he died?

If averages are published by a reputable website, shops can choose to use the average rather than "spot" price. In any case as XMR is more frequently exchanged for more stable goods or assets, the natural actions of buyers and seller will moderate fluctuations. However if you create a trading platform to trade averages vs spot prices that will tend to increase volatility, as short-term speculators benefit from volatility.

I already have done some rough work on the idea and have a bit of an idea what a good spec would look like.

Can you expand on that? Is the idea being actively discussed/developed anywhere?

There's a problem with audio balance towards the end (left channel only at 3:40). It would be a longer video but you could go into more OpSec - cookies/browsers, 2FA and password managers

Lots of prepper channels on Telegram with pdfs, eg https://t.me/PrepperCollective

If you want to install & update a FOSS app that's not on f-droid there's also Obtanium https://apt.izzysoft.de/fdroid/index/apk/dev.imranr.obtainium

I think a video featuring Xerxes, Yasmin and Zachary would be fun.