Im glad that someone else also thinks we need more collateral types on the Polygon Public Preview.
Be aware, that HiFi can only add tokens, that are available on Polygon. So this would typically remove things that are in the top 20, such as ADA, XRP, SOL, etc.
I’d recommend looking at things on this list Top Polygon Ecosystem Coins by Market Capitalization - CoinGecko for suggestions. But in my opinion, for our first collateral, we should onboard stablecoins, as these are the best collateral types as they change in price very little, which usually translates into very little risk and gives us all something easy to onboard. Perhaps some of the suggestions listed here? Adding a new market on Public Preview - #7 by Mainbrain