ESP32 is a great SOC. Watch out for RAM issues though. I have an e-reader using an ESP32 that only has 180kb or so of usable RAM which makes things very difficult to work with. You will need to specify that it has to be the versions that have addressable RAM. Unless of course, all updates are entirely firmware and the limited memory is just to hold the text editor buffer.
The Olimex board has 768KB RAM and 32MB PSRAM, more than enough. The original Ceres only had 2 MB of DRAM and 256 KB of VRAM.