Akelpad is a nice replacement. I use it on my work laptop. It’s locked down so I can’t install anything, but I can use portable apps!

https://portableapps.com/news/2024-10-23--akelpad-portable-4.9.9-released

Late response. I used to host radicale, but switched to MyPhoneExplorer a few years ago. I just sync from the laptop to the phone over bluetooth. It does contacts and memos as well. Reminds me of the old Palm Desktop sync.