Where does one go to start investing in IPO's such as these?
There are a number of sites that cater to social seed investing, and other early rounds, as well as sites specific to accredited investors. I started out on sites like Seedinvest, Fundersclub, Startengine, and a few others. There are other sites if you are writing really big checks, instead of little ones.
There are a few sites like Sharespost & Equitzen selling pre-IPO shares too, so you can express interest in a company and get some stock if someone doesn't want the very long lockup period prior to a liquidity event.
It is also possible to buy into a SPAC that has stated intentions to buy a pre-IPO company and bring it public.