I recommend starting with an aluminum board.
To me, aluminum is the bread and butter of this hobby.
Get to know aluminum. It’s not inherently high-pitched.
Acrylic is more a side quest. Same with other materials like wood and plastic. They tend to be softer acoustically but other factors can make them high-pitched as well as low-pitched.
No worry. You will eventually find yourself in these side quests. No need to rush into them.