According to WABetaInfo, WhatsApp is working on a feature that would allow you to move your chat history from Android to iOS (Android Central). The functionality was originally noticed in WhatsApp beta version 22.2.74 for iOS, and it looks to back up WABetaInfo's earlier finding in Android beta version 18.104.22.168.
Both upgrades indicate to a feature that might allow you to use the Move to iOS app to move your WhatsApp chats from Android to iOS. WABetaInfo also published a few images of the feature's potential appearance. According to the photographs, WhatsApp will request permission before proceeding with the transfer, and will then tell you to keep the app open and your phone unlocked while it migrates your messages.
WhatsApp began allowing users to transfer their conversation history from iOS to Samsung phones in September, and the capability was later expanded to include chat transfers from iOS to Google Pixels and other Android 12 devices. Allowing users to move their conversations from Android to iOS would obviously complete a loop, but it's unknown which devices will support the alleged functionality, as well as when (or if) it will be released.