Just google the country and e-Sim, and various choices will pop up. You can then decide how much data you need, and what the price is for that country, with various providers.
I went with Nomad, as they had some fairly small amounts of data available as a package for the country I wanted. I didn't need loads, as I had wifi much of the time, and I didn't want to pay for a lot more than I needed.
Others might have been cheaper if I had wanted lots of data. Or if it had been a different country. Or had wanted a phone number as well (to use for texts/calls - I didn't want that, as I wanted to access texts/calls from my normal number, and just not use it to make any calls; but some people do want that service as well, which is more expensive).
Different ones have apps that might be more/less easy to use and keep track of, so you might prefer one or the other of those. Also you can check what happens if you run out of data - how easy is it to top up with extra, and how much does the extra cost? that helps you decide what size package to go with in the first instance.