Looking to change my plan, but I have TiVo cable cards

I currently have Xfinity internet (600Mbs), Xfinity gateway modem & Xfinity TV. My TV plan is an older grandfathered plan and is no longer available. I also have an Xfinity cable box (with DVR) and 2 TiVO DVRs (w/ cable cards). All works good right now. 

I recently saw how there is an offer to add an Xfinity mobile line for free for 1yr to existing customers. I am thinking of possibly taking advantage of this by switching carriers and bring my own iPhone 13 to Xfinity. 

Also, cable cards have pretty much been phased out by Xfinity back in October 2024, but since I have been an existing customer, I am allowed to keep them.

I am also reading that if I change my plan in ANY WAY (add, delete, modify, etc), I will lose my TiVo's cable card access. Is it possible to add this Xfinity mobile line (free for 1yr) and still be able to keep everything else the same? If so, what is the best way to do it?