Still, I can get a Samsung Galaxy A20e for 150€ right now, which has about the same specs (actually slightly better) and spend two hours to get Lineage on it.
My point is, I do value my privacy a lot, even to the point of running my phone without GApps (which drops a lot of features), and I think these projects are absolutely awesome, but with their current offering those phones are simply not a general solution to someone with a budget.
A PinePhone/Librem 5 will also always be capable of running emacs/golang etc. which is not easily doable on Android if termux isn't possible anymore.
So can a phone running Lineage. The thing blocking termux is a config file; any phone that isn't locked down can handle it.
You're not getting all of the openness for free, but you can get a lot of it for free.
For now it's a config. As these things progress and get more locked down with each release in the name of security, it's going to be harder and harder and I don't want to scramble the moment it is practically impossible. I'd rather push for a free, open, libre hardware now so that the polish is there when there's no alternative.
If that actually happens.
I haven't seen any downward trend of LineageOS. I haven't seen any downward trend of Samsung hardware.
I've also noticed that nowdays, few phones are able to run more than one newer major Android version ahead because the OEM will simply not release the firmware needed to run newer versions and Lineage doesn't have the capacity to update/release their own firmware rebased against the latest Android, (I am talking about things such as the radio firmware, OnePlus is a famous example I know of).
Sounds like you value the open/libre aspect at $0. Not everyone feels the same way: Those phones are for people who value the replaceable battery and libre stack at $x where x > 0.