I have an iPhone 15 PM (eSIM ONLY) carrier unlocked and I have my T-mobile post paid number in it in IMEI slot one and have my landline ported to my IMEI slot 2 using US MOBILE's (MVNO) low data $10 plan for my second number (it does impact the battery running 2 IMEI's at the same time on a iPhone I do not care)
this way the data for the iPhone uses my T-mobile unlimited premium data for both IMEI's (well.....I believe that MMS/SMS pulls from the IMEI slot's 2 GB allocation. this is for me tiny)