CandyFace
The .pyxel format is just a container. You should be able to rename the .pyxel file to .zip and extract it's content. The extracted folder contain your layers as png (if you have any) and a .json with all the information you need.
Using a project of my own as an example, your json could look like this
{
"palette": {
"colors": {
"0": "ff000000",
"1": "ff222034",
"2": "ff45283c",
"3": "ff663931",
"4": "ff8f563b",
"5": "ffdf7126",
"6": "ffd9a066",
"7": "ffeec39a",
"8": "fffbf236",
"9": "ff99e550",
"10": "ff6abe30",
"11": "ff37946e",
"12": "ff4b692f",
"13": "ff524b24",
"14": "ff323c39",
"15": "ff3f3f74",
"16": "ff306082",
"17": "ff5b6ee1",
"18": "ff639bff",
"19": "ff5fcde4",
"20": "ffcbdbfc",
"21": "ffffffff",
"22": "ff9badb7",
"23": "ff847e87",
"24": "ff696a6a",
"25": "ff595652",
"26": "ff76428a",
"27": "ffac3232",
"28": "ffd95763",
"29": "ffd77bba",
"30": "ff8f974a",
"31": "ff8a6f30"
},
"width": 8,
"numColors": 32,
"height": 6
},
"settings": {
"ExportImagePanel_prefFormat": "0",
"ExportImagePanel_prefPath": "/Users/CandyFace/Desktop",
"ExportImagePanel_prefOverwrite": "false",
"ExportImagePanel_prefFileName": "Bubblebobble2",
"ExportImagePanel_prefTranspMatteColor": "4278190080",
"ExportImagePanel_prefScaling": "3",
"ExportImagePanel_prefSeparateFiles": "false"
},
"version": "0.3.109",
"canvas": {
"tileWidth": 100,
"tileHeight": 100,
"numLayers": 5,
"layers": {
"0": {
"name": "Layer 4",
"alpha": 255,
"tileRefs": {},
"blendMode": "normal",
"hidden": false
},
"1": {
"name": "Layer 3",
"alpha": 115,
"tileRefs": {},
"blendMode": "normal",
"hidden": false
},
"2": {
"name": "Layer 2",
"alpha": 255,
"tileRefs": {},
"blendMode": "normal",
"hidden": false
},
"3": {
"name": "Layer 2",
"alpha": 255,
"tileRefs": {},
"blendMode": "multiply",
"hidden": false
},
"4": {
"name": "Layer 1",
"alpha": 255,
"tileRefs": {},
"blendMode": "normal",
"hidden": false
}
},
"width": 100,
"height": 100
},
"animations": {},
"tileset": {
"numTiles": 1,
"tileHeight": 100,
"tilesWide": 8,
"fixedWidth": true,
"tileWidth": 100
}
}