Welcome to the forums! I'm not sure if Ivona has minimum requirements when it comes to the Android version. If it doesn't, yes you can use Ivona as your primary text to speech app. You won't be able to remove Pico but once you install all the necessary Ivona apps and data, Ivona should show up as one of the options in your settings.
Let me move this to the app sub forum just in case someone else has installed Ivona on a 2.1 device. I'll send you a link via PM.
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