Most of the OnePlus series, including older models, is fully supported by LineageOS, and unlocking the bootloader is straightforward. That were the most important reasons for me to go OnePlus. For me and my family there was nothing else comparably easily supported by Lineage with a good price/performance ratio. We currently use 6T and 8T models, that we bought used. The only downside for me is the lack of a notification light.
The BBC just reported that he resigned.