Why were you under that impression? No default encryption, no group chat encryption. Data on the servers, meta data, company resides in UAE and many more. Wenn don’t know what’s und er the hood of WhatsApp but what de know about Telegram is nauseatic
Lineage supports the phone not the phone Lineage. Okay, not the important thing.
What is cheap? For me, the Fairphone is the cheapest because the /e/OS support is announced at least for five year (FP 5: 8 years). So the device is not the cheapest but buying a new one whenever firmware updates run out is more expensive.