4 months into investing, didn’t realize I can invest my HSA dollars- recommendations?

In the past several months I’ve started learning about investing and opened a brokerage account, but have had an HSA for more than a dozen years, just sitting there. Myself and my employer add cash each year, but it’s uninvested and grows only a small amount of interest (w/ Fidelity).

I’ve realized that I can invest it and was planning to put ~10% in Spaxx and the rest in VOO… in general, is it better to do the entire lump sum at once or dca it? Also, if it’s invested, do I need to sale shares from Spaxx before using my HSA card to pay for something?