Croatia is a beautiful country and I've always wanted to visit - about what percentage of the population speaks English in your experience?
The younger generation usually do speak some English even in smaller "non-touristy" places.
The Croatian language seems fairly easy to learn to me but I'm biased on this being a native speaker of a Slavic language so your mileage may vary.
If you do decide to visit, I would recommend the Istrian peninsula around Pula, a beautiful Roman-style city. You won't have any issues with English there and you're gonna see much less tourists than you would in the more "traditional" vacation places like Zadar.
You can get reasonably priced accommodation in the surrounding towns and there is a huge nature reserve with beaches (cape Kamenjak). They charge a fee for entry but IMO it's quite affordable. The point of entry is the Premantura town but I would recommend against getting accommodation there as it's gonna be more expensive.
Personally I'd recommend looking for a BnB in Pomer, a small town 2-ish kilometers from Premantura. If you're a more "posh" traveler, Pula has nice and more-less reasonably priced hotels.
Also, you will want to rent a car there, the public transport is OK but won't get you everywhere...
Croatia is part of the European Union, and allows US citizens and other third-country nationals (non-EU/EEA/Swiss citizens) in, very easily. This includes during the coronavirus pandemic.
They also have a digital nomad visa, and they allow you to have the national health insurance, like Croatian citizens and EU/EEA/Swiss citizens, are allowed to have. It is quite a good deal.
Croatia basically costs about the same as the US, worst case scenario, and is often much cheaper. It is very nice in Croatia. Also, the people are extremely friendly and accommodating.
Also, coffee and cafes are a huge part of our culture. It is a place to gather and meet with people. We spend a lot of time in cafes. We are also a country where sports is a huge deal.
We all speak English, too. Anyways, I am a dual US|EU (Croatian) citizen living in Croatia (Zagreb, at the moment). I am culturally American, and have lived in the US almost all of my life. Split is also an amazing big city in Croatia.
If you want to experience what the "old Mediterranean" was like, you should absolutely spend time on the island of Vis. It is one of the most preserved islands in the Mediterranean. From post-World War II to around 1994, you could only visit the island if you had family there, as it had a Yugoslav military base on it.
Besides having an very rich history, it is just unbelievably pretty. There is a mountain on the island called Hum. There is also a famous blue cave nearby. Because it is so pretty, people call it the "Hrvatski Capri" (The Croatian island of Capri). You know, as in reference to the island of Capri in Italy.
Pictures and videos do not do justice to how pretty it is. If you want to see how pretty it is, the island of Vis is from 2:27 onward in this video:
Anyways, here is an awesome digital nomad in Croatia page to check out: https://www.total-croatia-news.com/news/digital-nomads-in-cr...
Here is the best site for learning about how to get the digital nomad visa--along with administrative stuff: https://www.expatincroatia.com/
I hope this helps.