If you want data only, you can get a 400 kbps unlimited data SIM (they also have eSIM) for 4 CHF per month from Digital Republic. Or 10 MBps for 10 CHF per month (see https://digitalrepublic.ch/en/private-customers-pricing/).
Note that it's not an actual subscription (although it's set by default to auto-renew), you can stop it at any time.
Note that it's not an actual subscription (although it's set by default to auto-renew), you can stop it at any time.