Is it possible to manually add utxos to the utxo database?
Could this be done by editing the chainstate file?
Note that, like "the mempool", there is no "the UTXO database". You can change the UTXO database for one node and only that node. Such changes will not effect other nodes and does not change the state of the network. By modifying a node's UTXO database, that node has the possibility of forking off of the actual Bitcoin blockchain.
Is it possible to manually add utxos to the utxo database?
Could this be done by editing the chainstate file?
Yes it is possible to modify a node's UTXO database. It is just several files which you can modify directly. Bitcoin Core uses LevelDB so you will need to use something that can read and write to LevelDB databases.