The new Outlook can open PST files—you just need an active Microsoft 365 subscription and the classic Outlook version.

Click “Search.” Gmail will display all emails older than your chosen date. Select All → Delete. You’ll see a checkbox above your emails. Click it, then choose “Select all conversations that match this ...

CNET has the full steps over at its site, but in Gmail you can use the "Forwarding POP/IMAP" tab to forward all your emails ...