Using Base/USD Oracle + internal exchange rate is in line with what AAVE does for other LSTs such as wstETH and sAVAX.
For example, here is [sAVAX oracle]. (Address 0xc9245871D69BF4c36c6F2D15E0D68Ffa883FE1A7 Details - Snowtrace), which uses sAVAX/AVAX rate from the contract and AVAX/USD price feed.
Since the major use case for an asset like ggAVAX is borrowing of correlated AVAX, this post also might have some relevant context.
Also important to note that stETH/ETH “depeg” occurred before withdrawals were enabled, which was arguably the biggest contributing factor to the whole situation, so it’s not exactly applicable to the current state of ETH and, especially, AVAX LSTs.