I just spent $200 on eBay for a OnePlus 6T (which is the newest phone supported by postmarketOS). First impressions: it is buggy as all hell and running what is essentially a desktop Linux OS on a 5 inch touchscreen does not work as well as I had hoped it would, but it is open source and it does kind of work, and I'm hoping with a lot more experimentation I can get it to kind of work slightly better