After a SPAC IPOs the common stocks become typically available 52 days after the IPO. Usually they would release an 8-K containing an audited balance sheet reflecting the receipt of the gross proceeds from the IPO. After the 8-K is released the common stock becomes available. You can read up more on the following site:
https://www.spacresearch.com/faq#spac-trading-units
So for PSTH this will be around mid september.
Hope this helps!