I’ve looked at the output of several vector graphics packages, and each one does a few “custom” things. For instance Sketch keeps meaningless nested group transforms. Illustrator stores encoded bitmaps and fonts inside the SVG (including when it doesn’t need to). Optimisers like svgo remove and convert most of these but may also replace one type of object with an equivalent other (e.g. rect vs path).
This is why I suggested that the only way that allows complete control over the process is studying the original SVGs in a text editor, and then surgically applying any custom replacements, converting the markup to fit the OP1’s engine where applicable. SVG is a complex format (you can alias and embed all kinds of things, all the way up to html pages, css, and other svg-s) and it’s very low chance chance if one just exports a file it would simply work.
What does the OP1 support? I remember the library it uses was posted earlier in this forum.