I use piped/newpipe etc. and simply support creators i watch via patreon/direct donations/merch. Less money for shitty ad company more money for creatives.
I think it will definitely ve backwards compatible(the wii could play gamecube games, the wiiu could play wii games, the 3ds could play ds games etc.) Nintendo has always supported at least one system jump except for wiiu to switch (for formfactor reasons) but switchgames are so small i dont think fitting them into their next console would be as challenging/impossible as shoving a disc drive into the switch.
you sure that usb has 32gigs? might be scam one that says it has more space than it does (would also explain the boot problem maybe?) but you said it launched fine once so i’m not sure/a mint iso won’t fit on 4mbs? but reformatting should definitely “reset” the usb… . have you tried it with a different one?