Wireless Joint

I'm going to be switching from Verizon to tmobile and was thinking bout getting the magenta max with free phone line 2+1. My question is would I just be able to pop that third line into my 1608 with an em20-g and have it qorked or do I have to go the tablet plan route?. Reason I ask is cause Las year I tried the tmobile Hotspot for 30 days. Worked great with the Franklin t9 but when I put it into my router it'll connect but no internet.

Yes you can use T-Mobile phone sim in router. Did it in the past. Now have T-Mobile home isp service. Would recommend getting that if you are eligible for it.
If still want to try and get T-Mobile phone sim can get info from this here about it.
viewtopic.php?f=32&t=888&start=140#p7409

Not sure what you have in mind. But if it is cost you can get 2 us mobile prepay plans for $60 per month. Then if you can get T-Mobile Home Internet for $50. That is cheaper than getting the three magenta max plans and you have something that is legit.

Not eligible for 5g home.

Well could be put on the waiting list and nag them. Have heard that work for others. Also people getting it at other addresses of people they know. Then using it elsewhere at your location.
But yes it can be done to use a T-Mobile phone sim in a router. Did it for a couple of years before got the home internet. Just need a router you can change the TTL in. Or if it works very well at your house without out door antennas could possibly tether a phone to a router.

For T-mo you could also use 'simplemobile'. US-mobile is an option depending on your usage. Their 'unlimited' plans are 'limited'. I think its 50GB/Mo. On the other hand seems I recall someone posting the simple done the same thing but their limit on their 'unlimited' plan is much higher. I can't remember if your IMEI has to match or not though, don't remember right off hand.