I have been running Storj on a 2 GB Pi 4, with a 2TB SSD attached - with about 1.5 TB available to Storj. It works very well now, but…
I had quite a few problems getting the storage setup nice and stable - there are some issues with some USB3/SATA adapters - although I bought my initial adaptor on a recommendation, I ended having to buy a second and change the storage mode used to access the SSD.
Another issue was that all the main chips run very hot on the Pi 4 especially when you are pushing the i/o. I managed to get a heatsink and small Pi controlled fan (Fan Shim) working quite well, but needed to solder the Fan Shim to GPIO header to get the necessary physical clearance.
Working like a dream now. Based on my experience - and I have been working in technical IT for 20 years - I wouldn’t currently recommend the Pi 4 route to “newbys” or those who aren’t prepared to get their hands dirty at the command line, (and possibly soldering iron) and are up for the challenge. Saying that, with luck, future firmware updates should improve the situation.
Hope this helps!