I can think of a couple systems that don’t use gold (or any other straight currency) :
The One Ring uses treasures as a measure of wealth, which above set amounts grows and gives you access to more. It’s not about spending your treasures, you’re not buying goods for currency (most of the time), instead you can afford stuff depending on your level of wealth.
Warhammer Rogue Trader (40k) while not a ttrpg still offers an interesting alternative. Since you’re extremely wealthy, earning and spending currency wouldn’t make much sense on a small scale, so instead you gain reputation with various factions by trading with them, which in turn gives you access to items you can grab freely.
The idea is the same, rather than using currency you have a measure of what you have access to. It can evolve up or down, varying what you can get over time, without the hassle of book keeping (or verty little of it).
Maybe a dose of realism? To hack anything serious from the outside it would probably take weeks or months of investigation, programming, testing, … So if the players don’t have the time, physical access, or previous knowledge and tools, that’s a big nay. It depends on what type of sci-fi though, if it’s the movie / tv type where hacking is a shortcut to anything in record time, welp.