I have the exact opposite experience with OSMAnd on Android.

The map rendering of OSMAnd is faster than Google Maps (using a 3+ year old smart phone with a low-end Realtek SoC). Like really way way faster/snappier.

My setup is a Chinese brand Android 10 with default OS (rooted)and OSMAnd+ from Fdroid.

The only possible cause I could think of is that CalyxOS is somehow missing proper video drivers for your Pixel?