That was one of the really cool features of the OG steam controller (and the deck too but I don’t use as much), pads can totally be setup to emulate a trackball and the haptics were weirdly good and giving you feedback. I found it really solid for games like warframe, that and gyro aiming (which I’ve never gelled with on the deck) felt pretty solid to me.
Otherwise, the trackpads can be used for things like rotary menus too which I definitely get a lot more use out of.
If you can swing it, Sabrent makes some nvme enclosures for the 2230 size the deck uses https://sabrent.com/collections/nvme-enclosures/products/ec-ne30 that are super reasonable price wise, https://sabrent.com/collections/nvme-enclosures/products/ec-snveis for full size and is also super reasonable. What I did for mine and my partner’s decks upgrading from a 512 GB ssd, if you have drive space you could do with one enclosure. I use the old ssd as a removable drive now so it doesn’t got to waste.
Ssd is the way to go for sure, SD card is nice to have but it’s very noticeably slower for some things, I tend to use it for emulators and games I don’t play frequently.
And even for fresh water, you have biofouling to worry about and what to do with the water after you’ve used it, can’t just dump it into the environment untreated.