Hmm… Wouldn’t be so sure. Some librarians have the power to selectively forgive late fees. They can give preferential treatment depending on their mood or the politeness of the person. You might also bribe a librarian to let you take out books from the special collection.
If the study group is very important to you, and the study group is on Facebook, then just have a Facebook. Deadlines and test info are not critical information that you need to receive in your pocket as soon as it is shared. You can check your anonymous Facebook account once a week through a VPN in a desktop computer and you will likely be well informed enough. If you have a friend that is both in Signal and that Facebook group, you can tell them about this and ask as a favor that they forward any critical time-sensitive info.
As for my response, mostly I use XMPP. I turn on my WhatsApp phone on every few weeks. People can message me via XMPP, e-mail, or Signal.
I have a little scanner. I can use the phone’s browser and log-in, using the scanner for the 2FA. But it is very rare that I use banking through the phone, as I do most of my banking via a desktop computer.
Bike, public transport, walking, and planning ahead.
On the desktop I do use Google Maps as it is quite efficient. Usually I plan ahead if I am biking somewhere new. I will often draw a path, write some street names at turns/crossings to remember, and pick some landmarks. Usually I am moving near places I know, so this is not task that comes up often.
At different points in time I have kept multiple fitness and nutrition logs (on websites and notebooks), but I rarely looked back at them. Now days I track rest times, hear rate, and running parameters while exercising, so I have a garmin watch and look at the output logs at the end of the exercise on the watch itself. It is not connected to any apps.
I make use of three devices: I. A Pixel phone running GrapheneOS has no SIM card. I have my apps, music, etc in this phone, and I use it as a mini tablet. It needs WiFi to get internet.
II. A PinePhone. I bought a large stack of the cheapest pre-paid SIM cards a while ago, and put in a new one whenever a SIM card runs out. I wrote a hook that, when I power down the device, a random IMEI is generated and written to the LTE modem. So, if I turn it off, swap the SIM, and turn it back on, I have a phone with a completely new mobile identity. This phone I can use to make calls and to share data with the GrapheneOS, but it does not have a static phone number. Usually it is off.
III. A Raspberry Pi 5 with a 4G LTE hat. This hat takes in a SIM card that is stable. So, this device is associated with a phone number and a persistent identifier, but it does not move. This is my phone number. SMS messages get sent to me via XMPP. If I am called, my XMPP also lets me know. I don’t have VoIP, so I do need to call back if I choose to. However, it is so so rare that I make a phone call that I have not bothered to implement VoIP.