If you buy small amounts overtime, let say $50 weekly and send to your ColdCard, you will have to pay on-chain transaction fees to consolidate your UTXOs or top up you Lightning balance, which lately could be anywhere between 30 sat/vb and 500+ sat/vb.
On Liquid it's 0.1 sat/vb. That's why it best to stack on Liquid, top up LN and when it make economically sense, you go on-chain.
I like to refer to this Unchained article to size my on-chain UTXOs.