A few weeks ago, when the Cobra Mk 5 became available for in-game credits, I figured I would put it through its paces with a short exploration/exobiology trip. Spent about a week round-trip, getting around 4.5k Ly from the bubble, scanning everything I jumped into, and landing at about a third of the planets I found with biological signals to scan them. The system scans earned about 200M credits. The exobio data netted me 2.1B credits from all the first footfall bonus rewards.
So go do that. You can have your carrier in a couple weeks.
I probably would have relied heavily on exobio for my carrier purchase if it had been a lucrative option at the time. It's still problematic as a means of grinding/farming credits because there are so many variables. How far do you have to go for FTDs? Depends. How long does it take you to get there? Depends. How many systems does one scan before one finds bio signatures? Not many, generally. How many biosignatures does a planet need to be worth landing? Depends. Is there an average exobio value per system? Not really. Can you provide a reliable estimate in terms of credits per hour? No. Is it easy to learn? Mostly. Is it fun? It can be. All of us can anecdotally say that our last expedition took X weeks (we almost never have a more precise measure than that), netted X million credits in Cartography data and X billion credits in exobio data, but the amount of time per day we spent, the ways we found unexplored systems, the criteria we used for choosing planets to land on, the ease or challenge presented by locating samples, and the pure luck (or lack thereof) of the RNG make it a highly variable task. Exobio is the best and worst of Elite all rolled into one. It is all the joy of exploring and all the sad oversimplification of seeing a galaxy of infinitely diverse combinations of the same few dozen things. It is the tedium of repetition and the brokenness of over-reward (which is vastly better than when it was under-rewarding). It is also one of the best ways to reconnect with the beauty of the game. It is a huge money maker, and yet, while anyone can make a fortune in it, they will log indefinite hours doing it, and no single experience is replicable. It's a way to play Elite that makes a lot of money. But it's something I would only recommend to someone who wants the experience to be as much about the journey as the reward. I wouldn't want someone to find themselves buried in frustration a hundred jumps from the bubble and unable to switch to something else on my account.I made my first billion just after the T8 came out (edit... for credits).
Within a couple of weeks of Exploring/Bio hunting I had enough to get a FC and outfit it.
Then used it to do some more Exploring/Bio hunting.
Whilst I haven't played much the last couple of weeks, I am back to a billion credits.
I didn't find it grindy, because 1 I like exploring 2 bio plays so well that I didn't even do that much to earn it.