I am going to go out on a limb here and ask if you've ever considered using a mini-machine.
I have one, it's a Uten uea001 and while it looks like a machine that you would give to your pre-teen, I can assure you, this little girl is an absolute workhorse. I bought her off of Amazon after my big girl (Dressmaker ss2402) went down on me and I needed something fast because I was working on a nine-patch quilt for my fiancé and I - it was coming up on fall and all of our comforters were so thread bare that one of them exploded in the washing machine.
She sews straight as an arrow and has a few other stitches, too and she's lightweight - like, I'm almost positive she weighs less than a full gallon of milk, she's that lightweight. On top of that, I'm able to carry her around using just my pinky finger and I have severe carpal tunnel syndrome, with tendon lock and arthritis. I was extremely surprised at how light she is, but she was able to handle a queen-sized nine patch quilt top without breaking a sweat.
My machine is no longer available on Amazon, but there are a lot of other mini-machines available (mine was originally listed at $160, but I was able to pick her up for $45) and the prices are pretty reasonable, even though there still seems to be a little bit of price gouging going on with the pandemic. If you're only going to use the new machine for straight stitching and taking her out and about, maybe consider going the mini-machine route? Whenever I'm able to travel back to Kansas City to visit with my family, my little girl is going with me, without a doubt.