Yes, it is possible to get the ABI of a contract without the source code. According to this research paper: https://dl.acm.org/doi/10.1145/3691620.3695601

Etherscan, an Ethereum blockchain browser, allows us to crawl ABI information via contract addresses to examine real-time information such as blocks, transactions, miners, accounts, etc. Similarly to the accessibility of contracts, some bytecode contracts do not make their ABI information publicly available.

This indicates that the ABI information for a contract can be obtained from Etherscan, even if the source code of the contract is not available. However, the contexts also note that not all contracts make their ABI information publicly accessible.