Phoenix can enable dynamic channel size thanks to their splicing feature developed by ACINQ on LNKMP. Zeus embedded node uses LND as backend & splicing is yet to be developed by LightningLabs. You can open channel to any public nodes. You can also receive LNURL-channel too

I'm not sure Zeus can automatically swap onchain sats to LN sats, you can swap the sats to LN using submarine swap lik boltz tho. Note that you can store sats onchain using Zeus SEPARATELY unlike on Phoenix, 2 layers 1 app