Alpaca supports the following coin pairs:

USD USDC USDT BTC
AAVE X X X
ADA X
ARB X
AVAX X X X
BAT X X
BCH X X X X
BONK X
BTC X X X
CRV X X
DOGE X X X
DOT X X
ETH X X X X
FIL X
GRT X X
HYPE X
LDO X
LINK X X X X
LTC X X X X
ONDO X
PAXG X
PEPE X
POL X
RENDER X
SHIB X X X
SKY X
SOL X X X
SUSHI X X X
TRUMP X
UNI X X X X
USDC X
USDG X
USDT X X
WIF X
XRP X
XTZ X X
YFI X X X