Raising the min Android version would be a proactive move to focus the development on limited set of Android versions and to keep the code modern and to avoid problems in the future.
If the app got released into F-Droid with the current min api, there will always be the chance you would need to choose in the future between having the best app or serving the highest amount of users and that would lower the value of this client compared to other clients.
I see that Raccoon for Lemmy has a great potential, but I am scared it will turn out as a generic client.
To see my point clearly, check out Summit for Lemmy, in theory in a couple of months both Raccoon and Summit would be in the same level in terms of functionality, the only competing factor in my eyes is the user experience.
Thank you for your valuable work on reviving this client.