YES, it is absolutely do-able!
I have had my own inner-router hooked up to a Swisscom Box since before the days of the Swisscom Box (back then it was an ISDN-modem).
Implementation can take anything from a minute or two, to a month or two depending what you are trying to achieve (in both cases, almost all of that time is planning, gathering the necessary hardware, and yeah -- learning some basic stuff and how to manipulate your hardware).
My implementation was in the month-or two category!
My inner-router is: firewall; NTP-server; DNS-server; advert-blocker; porn-site filter; manages a few important VLANs (Admin; Private; etc), and other stuff.
The only items that can "see" the Swisscom box are my inner-router, IOT devices, TV, and guests.
Simply pumping internet from the Swisscom Box to devices hanging off your inner router is in the minute or two caregory.
What do you want to achieve?
Chris
P.S If you want to host a server visible from the internet, I can try to get you started but you will need help from other members of this community (I use external hosting for such things).
EDIT: typo
EDIT: put my name on it!