S10e is great. It's what I've been using as well, but it doesn't get security updates anymore. Been using a custom rom which does get Android security updates, but there was a pretty serious SoC level security vulnerability which won't get fixed for the S10e.
I'll get a Pixel 8a instead. No headphone jack, slightly larger, only 1 physical sim. But can run GrapheneOS and have a long promised update period.
This is from 2023, but this might still be a good read on how to get to a very low watt idle build, there's a few more post on other older builds on that blog as well: https://mattgadient.com/7-watts-idle-on-intel-12th-13th-gen-the-foundation-for-building-a-low-power-server-nas/
The Linux Foundation has a mentorship programme which is really great, might be worth a look, although I am not sure how easy it is to get accepted: https://docs.linuxfoundation.org/lfx/mentorship/mentees
Music, dog.
If you are open to building something yourself this might be an alternative (disclaimer: I just know of this project but no idea how well it works): https://www.findmycat.io/
I've had success with this script https://gist.github.com/interfect/5f68381d55658d334e2bc4619d796476
You should be able to connect to the Chromecasts setup hotspot, get the IP of the Chromecast and then run the script.
The energy prices in Sweden were also mostly negative yesterday, and today as well. Although probably not quite as much as in Finland.
Obviously that was a controversial decision, but Red Hat probably contributes to Open Source more than any other company. To call Red Hat "OSS Hostile" is probably a little too much.
The most important thing, if you intend to do outgoing email, is to get a reputable hosting service, where you'd have few/none bad neighbours. Unfortunately that often doesn't come together with cheap, as cheap solutions often attract a certain clientele. I've also had more luck with slightly smaller (but still reputable) providers, i.e stay away from OVH / Hetzner and the like. If you want something cheap, it'd probably not be a good experience to self-host.
With my self hosted solution I have no concerns about deliverability, and only very few occasions had blacklisting issues (due to neighbours in the /16 range).
In many places call recording (or indeed processing of personal information which is highly likely to be present in phone calls) requires consent to be legal. I highly doubt this kind of processing is legal in the EU without both parties consenting.