I would recommend against using any stain since it will hide the grain to some degree. An oil based polyurethane varnish such as Arm-r-seal will slightly amber the maple and will accentuate the grain. Wipe on with a soft cloth and wipe off. I would suggest two coats, 24 hours apart. It is available in gloss, semigloss and satin. I would recommend against any water based finish since it will raise the grain.
If you want a matte finish, wipe on Rubio Monocoat Pure (one coat only) and let it soak in for 5 to 10 min and wipe off with a soft cloth. It will also bring out the detail in the maple and will slightly amber it. Very easy to apply and essentially mistake proof. Make sure you buff it with a soft rag to remove all residual Rubio.
Another newby question. I'm learning about my CNC by trial & error (more on the error side). But I'm enjoying the process. I'm ready to finish this practice piece (maple) but I'm not finding much information regarding finishing techniques for CNC pieces. Should I use sanding sealer before staining? Should I use sanding sealer and just apply a finish coat? How should I apply the sealer and stain/finish coat (brush, sprayer, rag, other)? There is a lot of detail in this piece and I'm concerned about pooling of liquids. Any help would be greatly appreciated. This is my practice piece before I attempt my finish on another piece to be included in a mirror frame.