So I am for the most part a lurker and a hobbyist. I've always been a bit of a techie, but over time decided I wanted to be more anti-consumption and such.
I started out with by doing my own calendar. I have a desktop that has my nextcloud and use it to sync my gnome calendar with fossify (with davx5). This was rather straight forward and gave me a nice confidence boost. This is mostly done on my local network, tho I am thinking of reading more into tailscale and getting a domain. The next move I did was to bring my todo list over. This was a bit tricky as many apps don't have a setting to support repeat todos and crossing one off might just remove the item entirely and kill the resets that another app set up. At one point I found the app super productivity. This app is basically perfect. Only downsides is that it is a bit more strict (particularly on the mobile app) about an ssl cert. There is an option to have the app sync with a local file. I thought I could be clever and just have nextcloud do the syncing and let the apps think they are working only off the local on their respective device. Alas there was a snag here. For some reason nextcloud will write the files with read only permission on the laptop, so I cannot add or cross off items. Then I remembered using some apps around a decade ago that worked off a todo.txt file. I figured maybe I could find some mobile and desktop apps and recycle the idea of letting nextcloud manage two way sync of a file and letting apps interact with it as if it were local. It seems like I have some winners here with sleek on desktop and ntodo.txt on mobile.
Just my humble story of selfhosting so I don't feel like a poser when listening to podcasts or lurking.
If you're looking for a different approach, I moved from Nextcloud to Radicale for my family calendars, which includes ToDo functionality.
From an app point, for Android I'm using Fossify Calendar (which I think you're using?) and Tasks.Org ToDo - and this definitely handles recurring tasks (inc. with different types of schedules)
From a remote access point of view, I have HA Proxy to convert the internal HTTP traffic into external HTTPS traffic (with Lets Encrypt certificate)
(Yes, I also have a VPN for other things... just focusing here for the calendar / todo)
I am using Fossify Calendar and ntodotxt on Android (GrapheneOS), and Gnome Calendar and Sleek on my laptop.
So for context in the discussion: I started with jtx board on mobile and using thunderbird todo. At some point I decided to try out Errands. When i crossed off items in it the item would be marked as done and any repeat settings were cleared. That was a bit annoying, so i decided to search for some apps that will play nice on both laptop and mobile. I then found Super Productivity. On paper i like this one way more and the time tracking is a nice extra. The issue is that either I either use its caldav sync stuff, but then mobile asks for an ssl cert. It does have a sync with file setting, but then for some reason nextcloud write the file as read only on my laptop.
I do want to set myself up with a reverse proxy so that I can tie the server at home with my domain, get an ssl cert and go back to Super Productivity. At this point I am enjoying selfhosting and want to expand my stuff a bit more, so the extra effort will be needed at this point. Keeping things local was more for a test bed before I have to be serious about locking stuff down and what not.